Your ‘logged-in’ status is stored in special cookies. If the cookie is removed, you are logged out.

You may be in Private Browsing mode or told Firefox not to remember.

Type about:preferences#privacy<enter> in the address bar.
The button next to History, select Use Custom Settings.

Turn off Always Use Private Browsing Mode
Turn on Remember My Browsing And Download History
At the bottom of the page, turn on Clear History When Firefox Closes.
At the far right, press the Settings button. Turn on ONLY
Cache and Form And Search History leaving the others off.

I don't think that you can prevent a user from logging out of a Sync account.

See unlinkFirefoxAccount and disconnectSync.

• https://searchfox.org/mozilla-release/source/browser/components/preferences/sync.js

You can possibly use code in userChrome.css to hide "Sign Out" buttons and "Sign Out" menu items, but that are a lot of possible places where you can disconnect and logout Sync or even visit the Firefox Account website.

What specific reasons do you have that you want to prevent users from logging out ?

Thanks for replies, "What specific reasons do you have that you want to prevent users from logging out ?"

I would like to control all our employee's firefox. if I login to all browsers with one firefox account, i can send tabs to device which i want. But if employee try to logout, i cannot do that.

Also i want to set home page which cannot be changeable.

I'am JR IT and i need to control them.

Can i do something about that?

For the homepage there is a policy available, for Sync it is only possible to disable the Firefox Account altogether.

• https://github.com/mozilla/policy-templates/blob/master/README.md#homepage

I will move the thread to Firefox for Enterprise as that might be more appropriate.

I'am confused,

I thought lock homepage with lockPref features, am i wrong?

BTW how can i get all firefox gui elements id or class list? For example i know just #personal-bookmarks id. Is there something like list?

To lock the homepage you can use a policy, but you can also lock the related pref directly via a lockPref() call in an autoconfig.cfg file.

//
lockPref("browser.startup.homepage", "<homepage-url>");

You can use the Browser Toolbox to get the selector for a specific element.

• https://developer.mozilla.org/en-US/Tools/Browser_Toolbox

I talked to our accounts folks and they do not recommend doing this. If you want to lock Firefox down to a specific configuration, you should use policies. Firefox accounts is not designed for sharing among multiple people.