Have a look at this article.

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

Suggestions in a login drop-down list that have a key icon in front are login suggestions that you need to remove in the Password Manager.

• https://support.mozilla.org/en-US/kb/password-manager-remember-delete-edit-logins

Suggestions in a drop-down list without a key symbol are autocomplete saved form data. Suggestions without a key icon are part of autocomplete saved form data that you should be able to remove by selecting this item with the cursor Down key and pressing Delete (Mac: Shift+Delete).

• https://support.mozilla.org/en-US/kb/control-whether-firefox-automatically-fills-forms

The preferences save. They just don't work. See image of settings and password suggestion screen. Thanks.

I refreshed Firefox as suggested in Terry's article of how to fix preferences that won't save and it worked! Sorry Terry for not trying that before I "thumbs down" your suggestion! Tom