Mahuki , if you are using system scrollto player.position and your layout is set to unbounded scrolling
then you need a condition to limit the scrollto,..combine a scrollx and y test (scrollx/y is center of screen)
system | compare if scrollx is bigger then, for example 500 , (value probably will be screenwidth/2)
system | compare if scrolly is less then, for example 500
action | scrollto player.position
so it will only scroll if these conditions are true
as always there are many ways to improve on this logic, but this is the basics
hope this helps