On the app it is strongly recommended NOT to put your nickname as your first and last name. You want to put your legal name, the one that will be used in an official league or tournament. Putting your nickname will not give you the best user experience and can even cause you to not receive the information you need.
How to go back and make it right.
On the app,
Click on More,
Click on My Account,
Click on your name,
Fix your first name and last name.
Click on Change My Name.