I have been trying to reply to a thread, and every ten minutes the I keep getting a login screen and loose everything I just typed. Just giving y'all a heads up.
If the forum does not work properly for you, why not write your reply somewhere else (I use Google Drive sometimes for this) and then just log in and copy-paste the readily written post.
Checking the "Remember Me" box (when you logged in) should have fixed the problem. If I were you I would PM one of the mods/admins describing the problem you're having.
Side note: I strongly recommend saving everything you write (such as in a text file) before you try to post it. In fact I'd even save every 15-30 seconds just in case of a power outage. But that's me, I'm very paranoid about losing my stuff.