Your Koji Username is used as a title on your profile and is also used in your koji.to URL.
For example, if your username is Koji, your "link in bio" is koji.to/koji.
How to change your Username
Press the button with your profile photo in the upper right corner.
Select Settings.
Press Username.
Enter the new name you wish to set as your Username.
When you've found a new name, press Save.
This username is now your koji.to URL.