Mike, you have simply adjusted the pressure switch too far.
Undo what you have done, ie turn the knurled button in the reverse direction until the pump runs again.
When you have the pump running, and the system is full of water, if the pump continues to run, turn he adjuster anticlockwise just until the pump stops.
Run the cold tap, the pump should start almost immediately.
Switch off the tap the pump should stop almost immediately.
Run the hot tap, pump starts.
Turn off the hot, the pump should run on for about 3 to 4 seconds.