When clicking/touching collision is detected for all objects under your touch/mouse..
If you want only the top instance to react:
on lightbulb touched/clicked
lightbulb pick top (instance)
> add your actions
Thanks for the help, worked great in your project, but couldn't get it to work on mine.
So I did when "button" is clicked, with condition "instance variable A" is = 0, you can click the button. Then I had an action to set "instance variable A" to 1, then system spawn new object "button(copy)". And I believe the new copied button still has default "instance variable A" as 0, so I can still click it.
Learnt alot from your project, and will keep the pick top/bottom instance for future reference!