How to Restore Firefox to Default Settings
Luckily, we can easily refresh our firefox browser to wipe the slate clean and go back to browsing as fast as the day we downloaded it.
Here’s how we do it:
1. type about:support on the address bar and press Enter key
on the top right side ( Give Firefox a tune up )
Click Refresh Firefox
don't forget : this action will not remove your bookmarks & saved passwords
It's only affected on your browser settings.