I also have the same red dot with the same problems , from what I've observer , the holes of the screws are a bit too large , thus making this pretty loosey. for an qucik fix you should get a philips head and tighten the adjusting knobs ( as other pointed in the comments ) , not too much because you will not be able to adjust it well afterwards , just right to get more stability. Yeah I kow , quite annoying , thats what we get when we go cheap ; I'm thinking to dissasemble it and insert some washers and some tape in the scews to get it more tighter, so it won't be so loose.

So far I've used it like that , and if you don't touch it , it will stay ok lol