Sometimes your Firefox preference settings may not be saved after you change them. For example, you may change a preference in your Firefox settings, only to have it set back to its previous value the next time you open the Settings panel.

The possible causes and solutions vary depending on whether you are unable to save a few specific preferences or if no preferences are saved at all. This article may also apply if, after updating Firefox, a Firefox Updated tab opens to a page stating You’ve been updated to the latest version of Firefox every time you start Firefox.

Refresh Firefox to fix the problem

The easiest way to solve this problem is to restore Firefox to its default state while saving your essential information. Besides resetting all preferences to default values, a Firefox refresh will also fix many other issues, including problems caused by extensions or with data and settings that are stored in other files in your Firefox profile. If you'd like to try a more precise fix, skip this section and try the solutions below.

1. Click the menu button , click Help, and select More Troubleshooting Information.
2. Click Refresh Firefox… then Refresh Firefox in the confirmation window that opens. Firefox will close to refresh itself.
3. When finished, a window will list your imported information. Click the Finish button. Firefox will open.
4. Select whether you want Firefox to restore all or some windows and tabs, and click the Let's go! button.

Specific preferences are not saving

If a specific setting in Firefox keeps resetting or you are unable to change a single setting but other settings save correctly, you may have one of the following issues.

Third-party programs changing Firefox settings

Some third-party toolbars and add-ons change Firefox's home page and search settings. To reset these, see Change your default search settings in Firefox and How to set the home page.

• See Remove a toolbar that has taken over your Firefox search or home page for more information.

User.js file overriding Firefox settings

If you don't have any of the above programs installed, or ifIf you followed the suggestions and certain settings change back each time you start Firefox, you may have to edit Firefox's configuration files yourself. Don't panic, it's pretty easy. Here's how to do it.

1. Open your profile folder:

   • Click the menu button , click Help and select More Troubleshooting Information.From the Help menu, select More Troubleshooting Information. The Troubleshooting Information tab will open.
   • Under the Application Basics section next to Profile FolderProfile Directory, click Open FolderShow in FinderOpen Directory. A window will open that contains your profile folder.Your profile folder will open.Your profile directory will open.
   Note: If Firefox displays an error after clicking Open Folder or if you are unable to open or use Firefox, follow the instructions in Finding your profile without opening Firefox.

2. Click the Firefox menu and select Exit.Click the Firefox menu at the top of the screen and select Quit Firefox.Click the Firefox menu and select Quit.
3. Open the file user.js with a text editor (like NotepadGedit, Leafpad, or KateTextEdit).
   • If there is no user.js file, these steps won't help you.
4. Remove the lines for the user preferences you want to be able to change. You can delete all the lines if you want to be able to change everything.
5. Save the file and close the text editor.

You should now be able to change your Firefox settings.

Firefox program file locks or prevents changes to certain settings

Your installation of Firefox may have been customized to add a program configuration file that locks certain settings or prevents certain changes from being saved. Follow the Reinstall Firefox step in the Troubleshoot and diagnose Firefox problems article to remove the Firefox program from your computer and then reinstall a new copy of Firefox. (Reinstalling Firefox this way will not remove your user data and settings, since those are saved in a separate location from the program files.)

Unable to save any preferences or settings

If none of your settings will save, if you get the Firefox Updated tab every time you start Firefox, or if you have tried the steps above with no effect, the file which Firefox uses to save your preferences may be locked or corrupted.

Locked preferences file

Firefox may be unable to save your settings if the prefs.js file (or the prefs.js.moztmp file, if it exists) is write-protected or there are other prefs backup files.

Corrupt preferences file

The preferences file may be corrupt, preventing Firefox from writing to it. If you delete this file, Firefox will automatically create another one when it needs to. Here's how to delete the prefs.js file.

1. Open your profile folder:

   • Click the menu button , click Help and select More Troubleshooting Information.From the Help menu, select More Troubleshooting Information. The Troubleshooting Information tab will open.
   • Under the Application Basics section next to Profile FolderProfile Directory, click Open FolderShow in FinderOpen Directory. A window will open that contains your profile folder.Your profile folder will open.Your profile directory will open.
   Note: If Firefox displays an error after clicking Open Folder or if you are unable to open or use Firefox, follow the instructions in Finding your profile without opening Firefox.

2. Click the Firefox menu and select Exit.Click the Firefox menu at the top of the screen and select Quit Firefox.Click the Firefox menu and select Quit.
3. Locate the prefs.js file (and, if present, the prefs.js.moztmp file).
4. Delete those files and any prefs-n.js files where n is a number (e.g. prefs-2.js).
5. Delete Invalidprefs.js if it exists.
6. Restart Firefox. You should now have all your preferences reset.

Other solutions

• Your problem might also be due to malware. See Troubleshoot Firefox issues caused by malware for details.
• Some software, like Advanced SystemCare with Surfing Protection, can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.

Based on information from Preferences not saved (mozillaZine KB)