cut paste from https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save

Custom settings are changes that you make to Firefox settings in the Firefox > Preferences window.
Such settings are stored in a pref on the about:config and saved in the prefs.js file in the Firefox profile folder.

You can use this button to go to the Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)

See also:

• http://kb.mozillazine.org/Preferences_not_saved
• http://kb.mozillazine.org/Resetting_preferences

cor-el i would like to verify as i want to trust the information provided but am nervous with the so mess after the big crash.

I want to be crystal clear, what part of firefox causes what i see thru the browser. Is my understanding below 100% correct? ---

In order of criticality to me:

NOT suggested to migrate to new Profile -- so you loose it (history) or recreate

▸ Preferences [FFox menu item/Preferences][KB articles refer as Custom Settings]:

1. Tab behaviour, How FF connects to internet, IPs blocked list, Setting for Remembering browsing history/clearing cache/clearing cookies, passwords captured
2. CANNOT be exported, so need to manually reselect
3. user.js (an optional file) and prefs.js
4. User preference settings. Not recommended to transfer if you had problems in your old profile. You may need to manually edit the paths in prefs.js to reflect the new profile location. If the new profile doesn't have the same extensions, you may have some unused preferences set by those extensions, but that usually doesn't harm anything.

▸ about:config EDITs

     question 1: logged separate ticket. is there any way to get a list of what entries have been modified e.g. addons page, navigation of the "get add-ons" i have going to explore page v overview page

TOOLBARs settings

• cannot be backed up. manually recreate

▸ Top toolbar - Holds URL and SearchBar

       question 2: where is the location and sequence of the icons stored under profile?

▸ bookmark toolbar

       question 3: where are the settings stored (show labels, smallest size) stored under profile?

▸ Tab bar location

       by default the Tab Bar is at the top of addon bar. I have mine underneath add-on bar..
       question 4: where is the placement of the tab bar stored under profile?

ADD-ONs

▸ Addon toolbar layout and placement

1. To migrate, first enable add-on Toolbar. Then essentially you need reinstall each add-on. Use list from Help/Troubleshooting, so you remember what add-ons you used. Sometimes the Addon icon does not appear automatically after install, so you need to customise addon toolbar and drag and drop it back to add-on bar-
2. Some add-ons are not installed from FFox Add-on page but the provider site e.g. 1password, Amazon Cloud Viewer

▸ Addons, themselves

1. Stored in folder called extensions.
2. Some add-ons are not installed from FFox Add-on page but the provider site e.g. 1password, Amazon Cloud Viewer
3. Each add-on has settings, and are stored in a myriad of places (about:config, preferences, custom settings (e.g. Tab Util))

OK to migrate to new Profile as suggested by KB article ---- ▸ Security certificate settings:"'

   cert8.db 

• If this is not copied, user receives "Get me out of Here" with Yellow Warning Triangle when going thru the library proxy

▸ bookmarks:

   bookmarkbackups folder and places.sqlite file

• Bookmarks can be backed up by manual export through button on Show All Bookmarks.
• You can alternately import a bookmarks HTML file if you wish to add those bookmarks to your current Firefox bookmarks.

▸ Page Zoom [KB articles refer as Site specific settings]:

   content-prefs.sqlite

• This history is cleared when ?
• Question 5: What menu item clears the page zoom history?

▸ Saved entries for web forms and the Search Bar [KB articles refer as Form history']:

• e.g. when i enter email address, it auto-fills with option and if multi entries in field, small popup showing me options

    formhistory.sqlite

• This history is cleared when you select "clear history under menu option Firefox/Preferences/privacy and select clear history (hint: it is hidden unless custom is selected)
• Question 6: is there a way to save only the web form history and clear the Search Bar history?
• Question 7: When KB article says "Search Bar" history - does this mean my history of surfing the internet (e.g. all the URLs i have visited). I call this browsing history. or it means what i have searched for? (e.g. the key words entered into Search Bar)

▸ Download actions for file types:"

   mimeTypes.rdf

• What action to perform when downloading certain types of files (save file or open with a specified application).

▸ Permissions [editted via about:Permissions]:"

• Per-site preferences for allowing cookies, images, popups, and extension install permissions.
• e.g. Websites that allowed to store content e.g. Amazon Cloud Reader to view book purchased offline - change setting to allow store data. Cannot set size limit.

   permissions.sqlite

▸ Cookies:

  cookies.sqlite

• Question 8: When I click clear session cookies versus all cookies, does that mean only the cookies from when i last opened up firefox?
• Question 9: Is DOM storage/information also stored in cookies.sqlite?

Outstanding (to investigate):

1. blocklist.xml
2. what caused the Access Denied problem, to other FF support account - as could not create new ticket using that account on FF forum (new account created as temp workaround)

File I dont use/dont need to copy but ok to copy per KB:

▸ Personal Dictionary

• persdict.dat
• Personal (custom) entries in the spell checker dictionary. Spelling Corrections.

▸ Passwords:

• I use 1password addon as FF option is not encrypted][Both of these files must be copied
• key3.db - Key database for passwords.
• signons2.txt (Firefox 2) or signons3.txt (Firefox 3) or signons.sqlite (Firefox 3.5)
• Saved passwords - Note: signons.txt was used prior to version 2.0.0.2.

▸ Saved Sessions [KB calls Session storage]

• webappsstore.sqlite - Only copy this if you deliberately keep and use many saved sessions

File no longer used in Firefox 27 (latest): chromeappsstore.sqlite

reference used • http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

See also http://kb.mozillazine.org/Profile_folder_-_Firefox

#1: There are too many prefs for all kinds of setting to give a recipe of what you lose and how to keep some settings. It is possible to copy specific lines from a prefs.js to this file in another profile or restore some settings after deleting this file in the current profile folder.

All prefs that show as user set and appear bold on the about:config page are stored in the prefs.js file.
This includes changes that you make and data that Firefox itself and extensions store as data/settings in a pref. It is

#2,3: The localstore.rdf file stores the toolbar configuration and some other data.

#4: Current Firefox versions show the "Tabs on Top" menu entry in the "View > Toolbars" and "Firefox > Options" menu and in toolbar context menus if the tabs aren't in the default position on top.
If the tabs are on top and the menu entry isn't available and you want to move the tabs below the navigation toolbar then you need to toggle the browser.tabs.onTop pref to false on the about:config page.
A Firefox restart is necessary to update the menu entry to either show or remove it.

Note that this pref will no longer have effect when the Australis code lands on the release channel (the Australis code will probably land in Firefox 29).

#5: See https://support.mozilla.org/kb/Clear+Recent+History

Clearing "Site Preferences" clears all exceptions for cookies, images, pop-up windows, software installation, passwords stored in permissions.sqlite and other website specific data stored in content-prefs.sqlite (this includes the page zoom).

Clearing cookies will remove all specified (selected) cookies including cookies with an allow exception that you would like to keep.

#6,7: Search bar history is the history of the (Google) search bar on the Navigation Toolbar.
All data saved from a form on a web page is included in form data, but you can't separate and distinguish the two.
Browsing history is the history of web pages that you have visited.

• Form History Control: https://addons.mozilla.org/firefox/addon/form-history-control/
• Tahoe Data Manager: https://addons.mozilla.org/firefox/addon/data-manager/

#8: Session cookies are always kept in memory and never stored to disk in cookies.sqlite
You can only clear specific cookies manually in the Cookie Manager or let cookies expire when you close Firefox to make them behave as session cookies.
Clearing cookies otherwise will include all cookies and doesn't obey exceptions that you made.

#9 Data stored in DOM storage isn't stored in cookies.sqlite, but is usually stored in the webappsstore.sqlite file or possibly as data in IndexedDB.

• https://developer.mozilla.org/en-US/docs/Web/Guide/API/DOM/Storage
• https://developer.mozilla.org/en-US/docs/IndexedDB

• https://addons.mozilla.org/en-us/firefox/addon/foundstone-html5-local-storage/