Hello rungirl60, try to delete the '''cookies.sqlite''' file and '''cookies.sqlite-journal''' files (if exist) in [https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data#w_how-do-i-find-my-profile profile folder] and check it again, in case cookies are corrupted. see for more info : [https://support.mozilla.org/en-US/kb/fix-login-issues-on-websites-require-passwords#w_remove-corrupt-cookies-file Remove corrupt cookies file] thank you

Hi rungirl60, I have had this problem as well. I also use Mozilla. In order to log out of Instagram via your PC, type in your address bar: www.instagram.com/accounts/logout It's a pain having to do it but at least it works! :-) Have a great day! :-D