Absolutely there is. :)I mean my name that you guys see on here
https://www.cubecraft.net/account/change-usernameAbsolutely there is. :)
Left from the conversation thing you see a head -> don't click on the head, but just move your mouse on it -> after doing that you see under your Profile Picture "change username", if you click on that you can change your username. :)
Weird you should be able toIt says I dont have the necessary permissions to do that. I used the link.