The Contest Commissioner can easily change the text that is visible in any owned box in the Contest.
This activity is done from the Players Settings Page, from within your Contest Settings.
Please note that the box text shown in the Context page will be abbreviated to 6 characters per word. If you require more detail, be sure to break your words into multiple shorter words. For example, WilliamJones will appear as "Willia." if you leave it as one word, but "Willia. Jones" if you break it apart.
Changing the Box Text from the Squares View
Near the top of the Players page, you'll find a simple view of your Contest Squares.
Simply click on any of the boxes within the Contest Grid and you'll be given options, including the option to provide New Box Text to replace the existing Box Text found in the Contest Grid.
Changing the Box Text from the Listing View
Below the Squares View, you'll find a directory listing of each owned box in your Contest.
Simply click on the Edit Button next to any player's name and you'll find the same options described above, including the option to change the Box Text found within the box.