It is not a problem. You only need to understand how this works in Firefox. "Use custom settings for

It is not a problem. You only need to understand how this works in Firefox. "Use custom settings for history" doesn't make changes to settings, but if you see this setting then this means that not all settings are the default and changes have been made. If you see this setting and you would change the cookie and history settings to the default then the next time you will no longer see "Use custom settings for history", but you get "Remember History" or "Never Remember History" (PB mode).