Try a Gmail account next. Yahoo seems to get more complaints than gmail.
So my dad has a Samsung Galaxy S4 and he has problems with his email. He has yahoo mail, but his email does not refresh. Usually when you refresh your email, or when you get an email, your phone would notify you. However, his email never gets any notifications and emails never loads. He has to check his emails through his computer. But whats the point of that??? You cant check your email when you are out! Also, his Yahoo frequently says to sign in even though he never logged out! But whenever he does input his password, it says that its a wrong password and that he needs to try again. Uhm... he knows his PW better than anyone else. Is it just Samsung or other phones have this same problem? Please help. Thanks!