The "topic" of your MV Live room is a small blurb at the top of your room to let visiting members know your mood, your goals, your deals, what you will be performing... basically anything you like!
To add your topic, each time you open a new live room click <Add a room topic> just above your live feed.
Type in your "room topic" and hit <Save>!
Need to edit your topic?
Hit <Edit>, change your text and hit <Save> at any point to edit your room topic to fit your show. :)