I'm going to confuse the issue with some fundamental fluid dymanics facts. The height of the water column flowing from the nozzle is dictated by the velocity of the water as it leaves the nozzle, period, end of story. (Go look at the fundamental ballistics in chapter one of your high school physics book - the same analysis applies.)
The velocity is dictated by the size of the nozzle and the flow rate of the pump. The pressure in the system is dictated by the resistance to flow created by the nozzle. Flow creates pressure - pressure does not create flow, contrary to popular opinion.
So, if you want to shoot the water higher, you need to increase the velocity as it leaves the nozzle. If you want to increase the velocity you need to:
A) increase the flow rate from the pump to each nozzle. For example you could use a VFD driven pump, which can be controlled with discrete outputs using the pre-set speed contacts available on most VFDs, or jog up and jog down inputs
B) or change the size of the orifice, using ed's suggestion or a modulating valve.