When creating a custom dynamic stamp, you may notice that the author name value is not set to the name you want:
It may display a userID or a PC name when you want it set to your actual name.
You can correct this following the steps below:
Navigate to File> Preferences> Identity:
You will see that the login name may be set to the userID and you cannot change it.
You can add your name to the First Name and Last Name to the respective fields to have it replace the author name as the login name