How soon does Firefox forget? If the problem typically occurs after you Quit Firefox and start it up again, the most common explanation would be that the cookie Google set was cleared. There are many possible explanations for that, for example:

• In Preferences, Firefox keeps cookies until you close Firefox, and there's no exception for Google cookies
• In Preferences, Firefox is set to clear history when you close it, and the Settings dialog includes Cookies, or Site Preferences, which would clear any exception you made for Google
• One of your extensions removes cookies
• Another program on your system removes cookies

To open the Preferences page:

• Mac: "3-bar" menu button (or Firefox menu) > Preferences
• Windows: "3-bar" menu button (or Tools menu) > Options
• type or paste about:preferences in the address bar and press Enter/Return

In the left column, click Privacy. On the right side, if the selector says "Firefox will: Remember history" then settings probably are okay, but you can inspect the details by setting it to "Firefox will: Use custom settings for history."

I am attaching some example screen shots showing Firefox set to expire cookies at the end of the session, but not to clear cookies or site preferences at shutdown, to avoid removing any Google exceptions/cookies you may have accepted that you want to survive to your next session.

Does that make sense?

To create an exception for Google, you can use the Permissions panel of the Page Info dialog.

While on Gmail, you can call that up using any of these:

• right-click (on on Mac: Ctrl+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 Allow permission.

Thanks for the detailed answer. Unfortunately, nothing helped. Perhaps the problem is related to the fact that logging in goes in two steps for this academic domain: first, you type full address, for example xxx@xxx.ac.uk; then it redirects you to the university site where you confirm your login. Nevertheless, this works flawlessly in Chrome, but not in Firefox. Any idea?

What happens in Chrome: does it skip that second step? So somehow the university's approval is remembered by Google, but I really have no idea how. Maybe it's a cookie set by the university site rather than by Google??

Can your U's IT shed any light?

Strange thing: once you login to your Google account (i.e., <something>@gmail.com), and then login to that academic account, Firefox does remember all. There must be a catch, but I am not sure where it hides. Anyway, this works now.