Firefox has multiple form filling features: * Password Manager - [[Password Manager - Remember, delete and edit logins and passwords in Firefox]] * Form History - [[Control whether Firefox automatically fills in forms]]; there are no site-specific exceptions * Address Autofill - [[Automatically fill in your address on web forms]] (North America only); also has a credit card option You can turn these on and off individually to see which one is responsible for the unwanted suggestions. If the suggestions persist even after these are turned off, it's possible the site is suggesting data you previously entered. You can flush the site's cookies and local data as a temporary fix but it's possible the site will keep doing it. To test that: While viewing a page on the site, click the lock icon at the left end of the address bar. After a moment, a "Clear Cookies and Site Data" button should appear at the bottom. Go ahead and click that. Firefox will ask you to confirm; go ahead and confirm. Then try reloading the page. Suggestions gone?