The stock screws are plastic junk, I found others at Lowes that are stainless hex drive. I also use two different bolt lengths for my three windshield heights. My touring screen (CalSci) has rubber grommets so those bolts must be longer and have washers.
The stock screen is worse than no screen at all so for summer I got the $20 ebay screen and cut it down to the height of the instrument cluster. Find what works for you, it takes a little trial & error but you will find something that you like.