in latest piplay, there are 2 clickable options.. bottom right of the piplay is a COG icon. click that and then at the top of the screen choose DEVICE tab.
in there are 2 clickable options 'Cool Colours' and 'Brightness' at this stage there are only those 2 options, but pimax have said they will offer more brightness options on the newer piplay maybe the debug tool for instance.
Personally, i prefer to use the Nvidia Control Panel to change my brightness and Contrast settings.
You wont really get the colours looking like a monitor because of the shutter glass on the lens, which many believe are to aid in reducing ghosting effects - removing those will make the colours bright and vibrant but will increase ghosting and could affect your eyes as the light sources will be much brighter and are directly in your eye! - safety 1st i say!