Changing mouth shape names for lip sync

I’m making some character rigs, and have drawn several unique mouth shapes for each character on several keyframes on the mouth layer. I know how to swap between mouths with drawing substitution and how to assign them for lip sync, but how do I change the names each mouth uses, so I can better differentiate between them and know which ones to use when assigning lip sync positions?

I know I’m not a Pro here, but you should be able to rename each drawing by pressing Ctrl+D or selecting it under the Drawing Menu.