I'm working on an adventure where a shop owner gives you a potion that gives you the ability to change your appearance. I have created a new item that uses a common event. In the common event, I had it so the Hero graphic is supposed to change, yet when the item is used in the test run, nothing happens and my character's appearance doesn't change. How do I get this to work?

Works for me.

My common event contains a single line that just executes "Change Actor Graphic" of the 1st character (important: first character only)
When I use a potion, it calls that common event and my character's graphic changes.

If you want it to change the person that uses the item, you will need to use scripts since the provided functions don't have such flexibility.

I realize what the problem was. Thanks!

Locking since you've found your issue!