The User tab contains properties regarding information about the user. These properties cannot be changed from the settings dialog, because they are part of the product registration. They can be changed using the license manager, but any change would require a new registration of the product.
Full Name - Full name of the user who registered this copy of Poseidon.
E-mail Address - E-mail address of the user who registered this copy of Poseidon. The presented email address must be a real one, or registration of Poseidon will fail.