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Type '''about:preferences#security'''<enter> in the address box. Look under '''Logins, ''' Note: For Firefox v56+ its; '''about:preferences#privacy''' Look under '''Forms & Passwords ''' Or type '''about:logins'''<enter> in the address box. +++++++++++++++++++++++++++++++ Turn on '''Remember Logins. ''' To check the passwords you have listed, press '''Saved Logins. ''' Press the '''Exceptions''' button and see what's inside. https://support.mozilla.org/en-US/kb/password-manager-remember-delete-edit-logins