Shut off the water supply upstream of the pressure reducing valve
Open a downstream faucet to relieve pressure
Locate the adjustment screw or adjustment bolt on the valve
Loosen the locknut if the valve has one
Turn the adjustment screw clockwise to increase pressure
Turn the adjustment screw counterclockwise to decrease pressure
Make small adjustments, a quarter turn at a time
Close the faucet and restore the water supply
Check the downstream pressure with a pressure gauge
Repeat adjustment until the desired pressure is reached
Tighten the locknut after adjustment
Inspect for leaks around the valve and fittings