Welcome to Just Answer, I will do my best to help with your problem
The pressure in the holding tank is set to 2 psi below the cut in pressure on the pump pressure switch.
It is usually set when it it installed and usually is not touched again. If the diaphragm in the holding tank fails the pump will short cycle (on then off then on again in quick succession). It is normal for there to be some pressure drop if more than one faucet is open at the same time.
I don't see any text in your last post and my screen has shown you typing for some time. I will switch to the Q&A format shortly in case there is some technical glitch