Okay, I think I see it is the Navigation Bar seems to keep all the URL's that is entered there. I noticed in the pull down menu that I had some sites I haven't visited in a year. I fiddled around a little and could not find how to delete those either..even the clear private data does not clear them.
I rarely enter URL's directly into the nav bar, I usually enter them in my Google search bar then click on the hyperlink. You can hide the navigation Bar and that takes them from view.. If you want to hide your tracks, use a search bar instead of the Navigation Bar in Firefox.
Mozilla Support has several instructions on how to customize the "smart bar". I disabled mine and it no longer retains the URLs
back on 2.something and much happier
Originally Posted by Cupcake