Hello there and welcome to Just Answer.
My name is ***** ***** I can help you with your Pandora Sign-In problem. In order to give you the best advise I need to know a bit more information on what you have done:
= The multiple types you have changed the password, did you tried do it through a mobile device? Have you tried changing the password ***** an actual PC?
I have seen cases when their systems could be having problems through one platform but not the other, so let me know if that works for you.