@Idiott22   Look around at all the posts in this forum.  Almost all of them are about this exact issue.  Here is the official explanation.

Unfortunately this does not work. I have cleared website data, cookies, cache, etc. None of the things mentioned in this link work. I sign in, the address changes to “sign in“ then immediately changes to “sign out“ and asks me to login again. Infinite Loop. Please advise on a working solution. Emphasis on working.

I'm having the same issue that a lot of people are having and it's been going on for a couple of months now. It makes me sign in every morning and when I put my password in it says I've reached my limit for unsuccessful sign-in attempts, after one attempt, so I have to go through the whole changing password processes which is quite annoying. After changing my password several times I finally decided just to click on Forgot Password and it takes me through the process but I put in my old password and it thinks it's new and says I've successfully updated my password. Why do I have to go through this every single day in order to read my email? Not to mention that I then have to go through putting my "new" password in on my phone to get my emails. Come on AT&T, or Yahoo, or whoever's in charge of your email system! Get this issue fixed!!! It's been going on way too long!