Authentication Failed using Pop

Had a working POP account that now gets Authenticated Failed. When it was working, thunderbird client was configured with User Name set to username

Problem started when I tried to add zoho docs. After that got the authenciation failed error messages from client and also got forced (I think) into a two stage authentication using cell phone texting.

Reading zoho documentation it says to use User Name username@zoho.com
So I changed that even though working before.

Turned on and off enable POP. That did not work. Saw some zoho documentation that I should click on save, but no save appears on the webpage that has enable pop.

Thanks for helping!