I use POP. Until recently all old emails continued to appear. I made the mistake (which I cannot seem to reverse) of trying to view my email in threads. It now only shows threads where there are unread messages. No matter what I try I can't see the other mail. I can search for it, mark it as unread, and it stays in the window, but if I click on something and then somewhere else, it disappears. I am missing a lot of mail so please help. Also tell me how to turn off the threaded view, it's driving me crazy.

I have a POP account and have not changed anything except the view. I have tried unclicking sort by - threaded, but it does not show the older read mail and it does not stay permanently selected - if I click on another folder and back to inbox, it is threaded again.