Resetting preferences (zoom, tabs, privacy, network, encryption, updates, where to save file downloads, etc.) is one of many procedures that can be helpful in troubleshooting Firefox problems. We'll explain two ways to do this.

• If changes to preference settings are not saved when you restart Firefox, see How to fix preferences that won't save.

Solution 1: Refresh Firefox

1. Click this Refresh Firefox button directly, if you are viewing this page in Firefox.
   This won't work if you are using a different browser or on a mobile device.
   • You can also find a Refresh Firefox button at the top of the Firefox about:support Troubleshooting Information page.
2. To continue, click Refresh Firefox in the confirmation window that opens.
3. Firefox will close to refresh itself. When finished, a window will list your imported information. Click Finish and Firefox will open.

Solution 2: Delete Firefox preference files

1. Click the menu button , click Help and select Troubleshooting Information.From the Help menu, choose Troubleshooting Information. The Troubleshooting Information tab will open.

   • Under the Application Basics section, click on Open FolderShow in FinderOpen Directory. A window will open that contains your profile folder.Your profile folder will open.
   Note: If you are unable to open or use Firefox, follow the instructions in Finding your profile without opening Firefox.

2. Click the menu button and then click ExitQuit .

   Click the Firefox menu , then click Exit. Click the Firefox menu at the top of the screen, then click Quit Firefox.Click the Firefox menu , then click Quit.

3. Locate and delete the file prefs.js (or rename it, for example, to prefs.jsOLD, to keep the old file as a backup). If you find more than one, a prefs.js.moztmp file or a user.js file, delete (or rename) these as well.
4. You can close the profile folder and open Firefox now.