Door locked, door unlocked, door locked

Why am I posting a picture of a door handle? Today at the doctors Audrey figured out how to lock it. I come to get her out of her seat she's flicks it locked I unlock it through my door I go to get her...she locks it. She is laughing now! (I am not)! This went on for quite awhile...seriously how does my 1 year old figure this out?