Every layout has to have an event sheet attached..
The event sheet tells the layout what to do..
https://www.scirra.com/manual/121/event-sheets
Events which are exclusive for layout one can be kept on an event sheet attached to layout one..
Events which are exclusive for layout two can be kept on an event sheet attached to layout two..
If you click on the layout in the projects bar on the right, you'll see it's properties on the left..
One of the properties is : Event sheet
This is where you can tell C2 which event sheet it should use for this layout.
(Normally C2 asks if it should attach a new event sheet when creating a new layout)