Hi JLN, did you just do a one-time clearing or did you change any other settings at the same time?

Normally, when you sign in to Google/YouTube the site sets a persistent cookie that can remain valid for an extended period. At worst, it should remain in place until you exit out of Firefox. You can review the specific expiration dates of cookies using the Storage panel in the developer tools:

https://developer.mozilla.org/docs/Tools/Storage_Inspector/Cookies

I should note that Nightly gets very frequent changes and on this forum, we generally focus more on the release version. You can check for similar complaints on the Firefox subreddit and/or file a new bug if needed:

• https://www.reddit.com/r/firefox/
• https://bugzilla.mozilla.org/enter_bug.cgi

I also looked in the storage panel. All cookies are session cookies. Is there any way to change this in the storage panel without deleting the cookies again?

Session cookies should persist until you exit Firefox. If you didn't use "Delete cookies and website data when exiting Nightly" then either the site doesn't set persistent cookies, or there may be a custom permission for the site. On the Settings page, the Manage Exceptions buttons in that same section should show any site-specific permissions.

So I checked the settings again and found out that I had "Delete cookies and website data when exiting Nightly" on after all. The reason for this is that after the problem occurred for the first time, I suspected this setting as a problem trigger and had therefore activated this setting for a short time, to then disable the setting again later. Now I have disabled the "Delete cookies and website data when exiting Nightly" again and will give another update soon. If the storage panel is anything to go by, the cookies no longer seem to be session cookies.

If you use "Delete cookies and site data when Firefox is closed" then you only keep cookies with an allow exception. Using "Clear history when Firefox closes" to clear cookies clears all cookies including cookies with an allow exception. Clearing "Site Preferences" clears exceptions for cookies, images, pop-up windows, and software installation and exceptions for passwords and other website specific data

After some time, I can now say that the problem seems to be solved. If something should still change, I'll get back to you. Thank you very much for the help!