how can I decrease the object's footprint? [HELP]

Isn't deco slot "0" large objects, "1" medium, and "2" small objects?

If the tray has medium deco slots, I think it accepts both small and medium items. If it has small slots only, it will only take small items, and the cupcake will have to be set as a small object to work like you want it to (this is most likely, I'm guessing it could have a medium slot in the middle to also accept larger items like cakes).

Doesn't have much to do with the footprint, but does have something to do with which object settings the tray accepts, and what the objects are set as.