By default, the game will use your social network name if you logged in with one. But you can go to your profile by tapping the Player Profile icon (head icon) in the top bar to change your name.
On Xbox, the profile name is tied to your gamer tag. You will need to change your gamer tag in order to change your profile name.
On Xbox, the profile name is tied to your gamer tag. You will need to change your gamer tag in order to change your profile name.