Hi,

If it's a UI change you can try to set it back in the add-on itself via Tools (Alt + T) > Add-ons > Extensions > Options for the add-on. You can also try to Remove the add-on. If it is currently disabled, it is best to Enable it before uninstalling it.

Also, you can update Firefox to the latest and check.

Firefox latest

If problems persist you can reset Firefox and start afresh.

The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information. Note: This will cause you to lose any Extensions, Open websites, and some Preferences.

To Reset Firefox do the following:

1. Go to Firefox > Help > Troubleshooting Information.
2. Click the "Reset Firefox" button.
3. Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish.
4. Firefox will open with all factory defaults applied.

Further information can be found in the Refresh Firefox - reset add-ons and settings article.

Did this fix your problems? Please report back to us!

If you would like to take a listing of the add-ons, changed preferences/settings etc. to quickly replicate the previous profile, please Copy all to clipboard (on the left of the reset button), and paste it into MS Office Excel, or OpenOffice/LibreOffice Calc, or notepad. However, it would be a good idea to check for the existence of the issue immediately after the reset.

Which addon did you install?

If you can't remove it in normal mode then start Firefox in Safe mode.

You can use one of these to start Firefox in Safe mode:

• On Windows, hold down the Shift key while starting Firefox with a double-click on the Firefox desktop shortcut
• On Mac, hold down the Options key while starting Firefox
• Help > Restart with Add-ons Disabled

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes