First, when using anothers computer, you should create your own user account. When you are done, you can just delete that account to keep your data safe.

Second, when you sync your data, it gets combined with the others data. If you want to remove your data, the only way is to remove it manualy bit by bit.

Changing the sync password only clears the data on the servers. This does not clear the data from the others system.

The second part of the instructions I read advise one to also change all one's other passwords . . .

If another gets a hold of your password information, they can log into your accounts with no problem. Changing the password is your only protection.

Note that only a password reset removes data on the Sync server. Changing the password merely disconnects other devices (the would need to reconnect using the new password).

You should never connect to a Sync account on a device that isn't your own because if you connect then data on the Sync server is downloaded to that device and isn't removed when you disconnect Sync. So that device would have all your passwords if you sync the logins and recent history and other items you sync. You would have to visit that person and remove that data on their computer.

You should change the password of the Sync account to prevent syncing new data to that device, but that doesn't affect data already synced to that device. If you do not trust that person then you will have to change all passwords after you have changed the password of the Sync account.

Fred McD, thanks for your response. You say,

First, when using another's computer, you should create your own user account. When you are done, you can just delete that account to keep your data safe.

But I thought that the whole point of syncing was to be able to access one's already existing Firefox user account from other devices. I couldn't do that if I created a new user account on any of those other devices, and I did not do that on the device in question that is away from home. Am I missing something?

when you sync your data, it gets combined with the other's data. If you want to remove your data, the only way is to remove it manually bit by bit.

To be clear, the computer away from home did not have Firefox on it until I came and downloaded it there and synced it to my preexisting Firefox account. It sounds like you are thinking that my data somehow got combined with Firefox data from the person who owns that computer? It did not. Or, if that's not what you meant, I guess you must have meant that the Firefox data that I generated on that computer has synced with the data on my personal computer and on my cell phone? That is fine. I just have decided that I'd prefer not to have my Firefox data accessible to people from that other person's computer while I'm not there. (I wish there was some way to just temporarily disable access to my Firefox account from that computer or something, because I will probably be returning and wanting to access my account from that computer again on multiple occasions.)

Changing the sync password only clears the data on the servers. This does not clear the data from the other's system.

So what does this mean for me in practical terms?

This is my key question, which I don't think you answered: "If I changed my password, would the other computer revert to requiring a password to open Firefox?" That is, if I were to change my Firefox password here at home, then if I had my Firefox account synced to another computer at a distance that was set up not to ask for a password before entering my Firefox account, would people there still be blocked from then on from entering my Firefox account? If so, then the following would be a moot point:

If another gets a hold of your password information, they can log into your accounts with no problem.

Cor-el, thanks, yes, that's my understanding, too. I don't mind resetting my Firefox password, but resetting all of my 200+ other account passwords to banks, shopping sites, etc. is just too much.

If you synced your logins to that other device then they are still there for everyone that uses that Firefox profile. If you want to keep using that device occasionally then best would be to create a new profile on each visit and remove the profile when you close Firefox and leave. You can possibly protect the logins on that device with a Primary Password if you want to keep this profile.

• https://support.mozilla.org/en-US/kb/use-primary-password-protect-stored-logins

Note that the PP is local to each profile and isn't part of Sync (each profile can have its own PP). If the owner of that other device doesn't know the password of the Sync account then you can at least prevent data on the Sync server from getting synced to that device.

cor-el, sorry I did not see your 11:42 a.m. response till now. That clears things up a lot, but how would a person on that computer access my data from that device even when Sync is disconnected? And how would I find that data once I'm on that computer again? Unfortunately, I didn't have time before I left to figure all this out and decide what I wanted to do. I was hoping it could all be solved remotely.

I did definitely want to have access to my preexisting Firefox profile when I used that computer, and that was the whole reason I synced it with my personal devices. I didn't want to have to reassemble all the bookmarks (probably over 400 by now) that I've set up on Firefox over the course of many years and re-set up my toolbar and other settings whenever I'm on that computer. That would take forever! So next time, I guess I'll just have to clear things out before I leave.

For now, it sounds like "protecting the logins on that device with a Primary Password" would be the way for me to go. However, I don't understand what you mean by, "Note that the PP is local to each profile and isn't part of Sync (each profile can have its own PP)." My profile has definitely been synced across devices--does that not make it a "part of Sync"? It sounds that way to me, but I guess I must be misunderstanding you. Thanks again...as an old boyfriend of mine used to say, "I'm slow, but trainable."

No, the passwords are only encrypted if you setup a Primary Password when using a specific profile on a specific device. The Primary Password is never used by Sync (for Sync it doesn't exist). To be able to upload username and password encrypted via the PP you first need to enter the PP to unlock the passwords. Then the data is encrypted locally with a sync key derived from the password of the Sync account before it is uploaded, i.e. on the Sync server there is only data stored encrypted with this sync key. The Primary Password never leaves this device. Note that you can use a portable Firefox installation on a removable USB stick that has its profile also stored on this US device and run this version without the need to install Firefox and download data from the Sync server.

You can install a portable (ESR) Firefox version to use this on other devices than your own computer. The portable version comes with its own profile folder and doesn't interfere with currently installed Firefox versions.

• https://portableapps.com/apps/internet/firefox_portable
• https://portableapps.com/apps/internet/firefox-portable-esr
• https://sourceforge.net/projects/portableapps/files/Mozilla%20Firefox%2C%20Portable%20Ed./

So right now, it sounds like I have a different Firefox password for each device that I've opened a Firefox account on? (I don't remember.) And so on that computer away from home, if I were signed out of Firefox on it, I'd have to enter my primary password and then a secondary password to get back in?

The USB approach would be great if I could use my synced data on it, or at least use my current profile. Otherwise, there would be no point for me. There's no way I could do this and access my current profile or sync?

The next time you visit the other system or contact its owner, remove all Firefox data files.

Next time you go out, may I suggest; http://portableapps.com/apps/internet/firefox_portable Mozilla Firefox, Portable Edition

https://portableapps.com/apps/internet/firefox-portable-esr Mozilla Firefox ESR, Portable Edition

A fully functional package of Firefox optimized for use on a USB key drive. A specialized launcher will allow most favorite extensions to work as you switch computers.

Firefox Portable is a 3rd-party build. Support is available here: http://portableapps.com/forums/support/firefox_portable

You can use sync to share passwords, bookmarks, and history. Anything else may not be compatible between different browser versions or computer systems.

FredMcD, where do I find the Firefox data files on that other person's computer?

And, about Firefox Portable, cor-el mentioned that too but made it sound like I could not sync it with my existing profile. You're making it sound like I can, though. From what I read, it sounds like the ESR version is intended for large organizations, so the other version would be more appropriate for me.

Also, I still don't know the answer to those password questions I asked on my last reply to cor-el. Thanks!

You can use sync to share passwords, bookmarks, and history. Anything else may not be compatible between different browser versions or computer systems.

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

http://kb.mozillazine.org/Profile_folder_-_Firefox#Navigating_to_the_profile_folder

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Type about:profiles<enter> in the address box.

As a non-techie, general statements and lists of links out of context of whatever question of mine each is attempting to address don't give me information that is easily usable at all. I'd really appreciate it if someone could just answer my last questions in plain English and then, if any links speak directly to those questions, please explain how so before or after each link. Is it possible that so many web pages are necessary to explain how to do what I'm trying to do?

A step-by-step bulleted list of all the things I need to do, in order, to achieve my objectives (which I think I've explained pretty clearly by this point) could be another good approach. Thank you...

Note: Firefox comes in three or more folders on all computers. They are;

Maintenance: (Programs Folder) <Windows Only> Firefox itself: (Programs Folder) And two folders in the profile of each user on the computer for each Firefox profile for that user.

The program itself can remain. But the profile(s) you created should be removed because others could find and use them.

As stated above, there are two Firefox profile folders for each user on the computer. One is used for user data. Bookmarks, settings, passwords. . . . . . . The other contains temporary and website data.

On my computer, the profiles are located: C:\Users\Fred\AppData\Roaming\Mozilla\Firefox\Profiles\cl2watk8.default-release and C:\Users\Fred\AppData\Local\Mozilla\Firefox\Profiles\cl2watk8.default-release

The part after 'Profiles' is the folder name. Note: The profile name Firefox created for you would be different. You need to locate your folders on the others system and remove them.

Thanks, Fred, I think that should clear up that part of my problem.