Options menu reference
Options|Set markbook owner
Set the owner of the markbook. Select the name of the user to be the new owner and click on the Change Owner button.
A markbook only has a single owner, so if you change the owner to another user, you will not be able to use any of the commands exclusive to the markbook owner the next time you open the markbook. Refer to the Working online topic in the Introduction section for more information about the markbook owner.