Make sure you don't have any other password managers installed which will override the built-in one.

You can't have multiple Password Managers enabled at the same time, if you have others like Trend Micro Password Manager or RoboForm, the builtin Firefox Password Manager will be disabled.

If you have the "Trend Micro Password Manager" installed, uncheck the password Protection box in its configuration or uninstall this application via the Windows Control Panel.

You can open the about:policies page to see if policies are active and if errors are reported.

• https://support.mozilla.org/en-US/kb/see-active-policies-firefox-enterprise

Thankyou for your suggestions but no other password manager i checked that before removing firefox. I have on Brave but that was only added when I had the problem with Firefox. Both Brave and Edge remember passwords wth whatever is upsetting firefox. Looks as if I will have to go with Brave

Start Firefox in Troubleshoot Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or if userChrome.css/userContent.css is causing the problem.

• switch to the Default System theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Troubleshoot Mode start window

• https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

See also:

• https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save