What is your computer system and Firefox?

Not sure if I understand the problem. There is the Password Manager. But there is also a 'form filling' option.

Windows 8.1 with Firefox 46.0.1 Even if I un-install Firefox and download it again the id and security question answer remain. I have no problems with other logins nor another on-line bank. I have checked menu > options > security and nothing is listed. I have even changed the id and security question but the new ones appear. I have not told the URL to remember anything.

Type about:preferences#privacy<enter> in the address bar.

The button next to History, select Use Custom Settings.

Turn off Always use private browsing mode Turn on Remember my browsing and download history At the bottom of the page, turn on Clear History When Firefox Closes. At the far right, press the Settings button. Turn on Cache and Form And Search History leaving the others off.

Unfortunately this didn't fix it. Even if I un-install Firefox and reload it still comes up with my id. So I have switched to Chrome temporarily and will switch back when a later Firefox release fixes it.

Thanks for your help.

What you can do is disallow cookies for that site.

Cookies are sent by websites. You can tell Firefox to not allow sites that you choose by following these directions.

Type about:preferences#privacy <enter> in the address bar.

The button next to History, select Use Custom Settings.

Under History, turn on Accept cookies from sites and Accept third-party cookies. At the far right, press the Exceptions button. Place those websites you don't want here.

I've discovered the problem! it is caused by the add-on "Blur" with this Firefox release. If I disable or remove it I don't have the issue.

FredMcD, thank you very much for trying to help me fix it.

That was very good work. Well Done.