How do I select a title for my Avatar Banner in Rocket League?
Titles are equipped to your Avatar Banner from the Profile settings in the Main Menu. Titles aren't shown in your inventory. These are displayed on the scoreboard and during the replay after a player scores a goal.
To equip a title, from the main menu:
Select Profile
Select the icon to the right of Choose Banner
Select your title
Your selected title should now be visible on your banner