every random seconds needs to be random(1,5) instead of a dash (random1-5) makes them spawn like crazy. also the spawn event random((12,1024, 1200) that Y coordinate is spawning them off the bottom of the screen - change to 0 if you want them up at the top.
for easier debugging you can try setting your background to invisible and your squares to visible, it helps a lot when setting up your event systems.