Each of the objects should implement the interface.
Then you can either “cast to (interface)” or just “call (interface function)” on the object.
In fact, I do exactly this in my “interactable” system.
In your case, you’d simply define a “Set Text” function on the interface, and call that. If the name “Set Text” interferes with some existing function of the same name, call it something slightly different, like “Set Interaction Text”