Yahoo Mail Sign In

OS is Win 10. A few days ago Yahoo mail started requiring signing in each time after closing and reopening Firefox. I'm certain I've changed nothing to prompt this. (The stay logged in box when signing in to Yahoo is checked). I've tried everything in Google searches including allowing cookies, resetting Firefox and a few other things to no avail. Edge has the same problem, but my Ipad's OK.

Any help would be appreciated.

 

As a footnote, all my other fav sites are keeping me signed in.

 

Apparently this was a password problem. I went to the ATT Yahoo "change password" section but didn't actually change my password, bailing out by canceling before making a change. This appears to have solved the problem. This was actually an Ipad problem also although I mentioned above it wasn't. Hopefully this solves the issue. Perhaps I should change the password as maybe my account was hacked. Any thoughts?