To change your username and subdomain of your Artist Page, you must go to "Settings", "Profile" and make the modification in the "Username" field.
Very important:
1- The username and subdomain must be unique. Different from that of any other user.
2- As you know, every time you log in to your account, you must enter your username and password. Indeed, when you change your username, you will have to put your new username to be able to log in.
That's all for this tutorial! You have learned how to modify your username and subdomain.