How To Work Ntbot I Have A Shower With Four Knobs...one Is Supposed To Work The Water Pressure...I Have No Idea How It Works.?

I have a shower with four knobs...one is supposed to work the water pressure...I have no idea how it works.? - how to work ntbot

I have no idea how to build a plant with four buttons shower. It is supposed to put the pressure on the water, however, raise the volume, is the hot water. Help!