When I'm in Yahoo Mail, I ought to be able to "sign out" and then sign in as another user. But lately I've been unable to do that as Yahoo "recognizes" my last sign in, and automatically fills it in. When I sign out and on, I should in theory (and by experience) get a blank sign-in sheet. Why is this? Am I the only martian on the block with multiple e-mail addresses, and all these headaches?