KG,

No adjustment screw. The float arm has a clip that you can adjust the float either closer or further away from the fill pipe. It’s a pain in the butt. Very bad design.

I’ll eventually replace it. My wife just said tonight her toilet is having issues...

We have very hard water in KY. I keep a couple of fluidmaster tank rebuilt kits in the garage, they're maybe 15 bucks for the whole set. At the first sign of trouble, I look carefully at the parts. I usually find buildup around the flapper and fluid valve. Its's a simple matter to shut off the water supply, gut the tank and rebuild the guts. It usually takes less than half and hour and requires no tools, especially in a house as new as yours. It's a small investment for peace of mind.