You can easily change your user name. It's done right in the iOS app.
To do this, log in to the Fyrrr app. At the bottom of the screen, tap the "Profile" icon in the main menu. You can change your user name by tapping on the orange "Edit Profile" button.
Here, you can change your profile photo, enter your first and last name, and enter your bio details. You can also edit your interests to receive recommended video content in your feed.