The pressure setting on an accumulator tank should be just barely above the cut-on pressure of the pump. That way the accumulator tank will empty before the pump cuts on.
However, the accumulator tank setting can not be why your pump won't shut off. When the tank gets full, the pressure will go up to shut off the pump regardless of any settings.
Now, if you are actually talking about the bypass setting on the pump, disregard my post. My post only applies to actual accumulator tanks.
If the pump bypass setting is set too low, the pump will never turn off.
Bobbo and Lin
2017 F-150 XLT 4x4 SuperCab w/Max Tow Package 3.5l EcoBoost V6
2017 Airstream Flying Cloud 23FB