then you are doing it wrong,there is a reason they are called global,
try this.
create one event sheet for each level you have.
copy paste all events to all the event sheets you have.
Do not include one event sheet to another.
lets say you have 100 levels
set global variable "level" to 0
when you finish a level
on end of layout "level 1 "set "level:=1
on end of layout "level 2 "set "level:=2
on start of layout "level 2" "level"=1 destroy "level 1"
on start of layout "level"=3 "level"=2 destroy "level 2"
etc