I work with a Mac and Yahoo does not work well on this platform.
If I want to adjust my account or check if missing mail has been put in a Spam box it takes me several tries to log on to the account page. It wont let me log out but, fortunately, it seems to log out for me if I don't talk to it for a short while.
My email is a BTOpenworld account and any attempt to get to their website always takes me to Yahoo. It's a pain in the bottom.
I have to put up with it or change to another provider. There seems to be nothing I can do about it.
Good luck.