From the Model Mayhem FAQ:

How do I add Praise to or edit an existing credit?
You can see all your sent verified credits from My Credits:

Use the Sort & Filter option, and set the View to "All" to see all your verified credits, including the unapproved ones you've sent out that haven't been accepted.

Adding praise to and editing an existing credit is easy!

  1. Go to My Stuff
  2. Open My Credits
  3. Find the person you want to leave praise for or make changes to. You should see something like this:

  4. Type in what you want for the Praise and click "Add Praise" - it's that easy!
  5. You can also click "Edit Details" to change your other information, like how many times you worked together or when you last worked together.

The other person will have to re-verify the credit to accept the praise, but at that point it should appear on your credit.