Dose anyone know I can change my username even if I already changed it once?

The title speaks for itself 

That is not an option in chess.com.

Although if you REALLY want to change it, you can contact support.

And they might change it for you.

🗿🗿🗿

You can't, sadly. If you're willing to, you can make a new account and close this one, with your desired username. But if you're not willing to do that (which I assume most people probably arn't willing to give up an old account), you can contact support. I've closed my old account before and they said something like 'if it is simply a different username you seek, please contact support'. Send a message directly to support and they will help you  

It says right there, you can change it one time.