You can only change the Primary Password if you know the current PP. If you do not know the current PP, then your only option is to reset the Primary Password. See this article for more detail. *https://support.mozilla.org/kb/reset-your-primary-password-if-youve-forgotten-it You lose all currently saved passwords, so you may want to backup the logins.json and key4.db files in the Firefox profile folder to see at least what websites you have stored or if you want to retry in case you remember the PP. *https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data