Adding a new email

I had my email on thunderbird for years. Changed computers and one would not work. It said the password was wrong. So I deleted it and tried to reinstall it but it still says the password is wrong. When I log into Yahoo I use the same password and it works. With Thunderbird I get a message that states : Unable to log into server. Probably wrong configuration, user name or password. I have put other Yahoo email configurations in and they seem to work, all on the @att.net platform. Anybody got a helpful idea. Charlie Parsons bmwrats@att.net