You can only change your username once

When you create a Facebook account, your profile or page is automatically assigned a username, which is essentially your name plus a few numbers. It’s relatively hidden: it only appears in the URL of your Facebook profile, which you can send to people so they can find you on Facebook.

However, your Facebook username is different from your Facebook name. Your Facebook name is what other users see on your profile or when they communicate with you on Messenger.

You can change your name and username in a few quick steps.