Confusing question. Username for what? Thunderbird does not install or run on smart phones so I do not see where that fits in.

Not a confusing question. I want to log into the forum from my cellphone. I setup the log-in from my desktop without realizing that the keyboard didn't have underscores. I'd rather not sit in front of a desktop when I can take the phone with me. Why is that confusing?

I just created my username on my desktop.

This could be a username for a user account on your PC. Username for your subscription to ebay. Who knows?

Well this is a support forum for Thunderbird email client. You do not specify what username you are asking about. Email accounts use usernames. This forum is not really for support of actually using the forum itself.

This forum is free. Just make a new account with the username you want. It is not like you will get charged extra.

Wow!!! Is everybody arrogant up here. I probably used the wrong term (username) instead of my login name for the forum. You people really need to take a deep breath. It's Christmas time people. We aren't all as smart as you seem to think you are. Cut us dummies some slack.

Sorry you are offended when asked to clarify your questions so you can get an accurate answer. The Internet is a dangerous place.

If by "you people" you mean the Thunderbird users that volunteer their time to try to help people use Thunderbird, maybe you would like to become one of those"you people" and try to help out.