Options menu reference
Options|Set class owner
Set the owner of a class in the markbook. Select the name of the user to be the class owner and click on the Change Owner button.
By default, each class in a markbook does not have an owner. This means any user able to open the markbook, can edit results in all the classes. By setting a class owner with this command, only that user and the owner of the markbook can enter results into the class.