You can try to delete the cookies.sqlite and permissions.sqlite files in the Firefox profile folder.

You can use this button to go to the currently used Firefox profile folder:

• Help > Troubleshooting Information > Profile Director: Show Folder (Linux: Open Director; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox

You can inspect and manage the permissions for the domain in the currently selected tab via these steps:

• Click the "Site Identity Button" (globe/padlock) on the location bar
• Click "More Information" to open "Tools > Page Info" with the Security tab selected
• Go to the Permissions tab (Tools > Page Info > Permissions) to check the permissions for the domain in the currently selected tab

Also see: Cookies - Information that websites store on your computer Permissions Manager - Give certain websites the ability to store passwords, set cookies and more

Firefox shows "Use custom settings for history" as an indication that at least one of the history and cookie settings is not the default to make you aware that changes were made.

If all History settings are default then the custom settings are hidden and you see "Firefox will: (Never) Remember History".

"Use custom settings for history" stays only selected if at least one of the History or Cookie settings is not the default to make you aware that changes from the default setting have been made.

I deleted the cookies.sqlite and permissions.sqlite files from the profile folder -- same problem. The cookies repopulated when Firefox reopened but settings still are not retained. Firefox opens as if the program had just been downloaded and asks if you want to take the tour. I can see many normal cookies that are stored -- from the site mozilla.org. Expiration dates are both next day and long into the future. Could a key cookie have been accepted for one session only by mistake? Should I try "resetting" Firefox?

I am now okay on how to get the option on how long cookies will be stored. Not very intuitive but I get it.

Thanks for the help but we are not done on the retension issue for settings in a single profile.

You can check for problems with preferences.

Delete a possible user.js file and numbered prefs-##.js files and rename (or delete) the prefs.js file to reset all prefs to the default value including prefs set via user.js and prefs that are no longer supported in the current Firefox release.

• http://kb.mozillazine.org/Preferences_not_saved
• http://kb.mozillazine.org/Resetting_preferences