What if you turn the screw and nothing happens? That’s called "it’s broken," my friend. Your Watts valve might be internally clogged with mineral deposits. Time to replace the whole thing. Not the end of the world, just a minor setback.
WATTS W-M115-EN-202005 คู่มือการติดตั้งวาล์วลดแรงดัน
What if you over-tighten the lock nut and strip it? First, scold yourself loudly. Then, calm down. You can usually buy a replacement lock nut at a hardware store. I may or may not have done this. Twice.
And whatever you do, do not try to adjust a valve that is actively leaking from the adjustment screw. That means the internal diaphragm is shot. Call a plumber and bribe them with cookies. Some battles are not ours to win.
