There are two ways that Firefox can log you into a website: '''(1)''' Sending the site a '''cookie''' previously set by the site that has not yet expired, and/or '''(2)''' Entering your login information using the '''Password Manager''' '''Method #1''' is completely seamless, you won't even see a logon page. To resolve this issue without affecting other sites, you have two choices: (A) Sign out of Facebook when you are through with it. Facebook will revoke your session and any saved cookie will not get you back in. You probably have noticed the little "triangle" menu icon in Facebook that has this command. (B) Set Firefox to only store your Facebook cookie until you close Firefox. This is known as a "session" cookie or "session-only" cookie. You can modify website permissions using the Permissions panel of the Page Info dialog. You can call that up using any of these: * right-click a blank area of the page and choose View Page Info > Permissions * (menu bar) Tools menu > Page Info > Permissions * click the padlock or "i" icon to the left of the site address, then the ">" icon, then More Information > Permissions Scroll down to "Set Cookies" and uncheck the "Use default" box, and then select the permission you prefer, for example, Allow for Session. This won't immediately remove existing cookies. To do that, you can switch over to the Security section of the Page Info dialog, click Show Cookies, and review your FB cookies there. If there are cookies that have an expiration date other than the end of your session, you can remove those and the next time FB sets them, they will be set to expire at the end of your session. Note: If you have Firefox set to automatically restore previous session tabs at startup, then your session never actually ends. In that case, you might need to use some additional options/features. Let us know... '''Method #2''' can be controlled by setting a Master Password so that anyone trying to auto-login to sites needs to know that before Firefox will sign in. More info: [[Use a Master Password to protect stored logins and passwords]]. Does that help?