Although not the original intent of this thread, I have a question that belongs here given the title of the thread.

In what file are credentials kept in Mozilla? Or, more specifically, in what file does Mozilla track whether or not to keep credentials for a specific site?

I accidentally told Mozilla to never keep credentials for a site I frequent all the time and I am now stuck having to enter my login and password everytime for the site. How do I reset this? I have already tried resetting all my privacy information including cache, passwords, etc.