In an emergency situation at a conference, I needed to display a presentation via Apple TV; however, I couldn't remember my new Apple ID at the time. A friend signed on, using his account, in order to download Mountain Lion to accommodate Mirror Play . Upon returning home, I have since upgraded to Mountain Lion using my ID; however, I continue to receive update notices regarding Apps that my friend purchased in the past. How can I get rid of notifications to update Apps that are meant for him?? Sorry, but I'll need fairly explicit instructions as I'm somewhat new to iMacs. Thanks for any assistance.