Run water until the pump comes on and note the pressure on the gauge when the pump starts, shut off the water and note the pressure when the pump shuts off.
That gives you the on/off switch settings of the pump/system. You may have to do that a couple times.
Shut off the power to the pump.
Shut off the water past the pressure tank to the house.
Completely drain the water out of the pressure tank.
Check the air pressure in the tank. If you get water or water vapor, the tank bladder is busted and you need to replace the tank.
The pressure has to be 1-2 psi less than the turn the pump on pressure; 30/50 gets 29-28 psi with no water in the tank. Adjust accordingly.
Close the drain valve on the tank and turn the pump power on noting the pressures as above. You may have to repeatedly run water and such and then adjust the pressure switch if needed to get the pump on at 30 and off at 50 or 40/60 etc..
Turn on the water to the house.