change air setting on cpap

i have a fisher & paykel HC220LE and would like to know how to change the setting on it. someone told me in this forum a couple of weeks ago but i didn't have the buttons on my model that he said i needed. the only buttons on the cpap is the ramp button and a very difficult tiny dial to turn up/down the water temp in the humidifier; plus, of course, the on/off button. i find on the side of the unit a small plastic cover that when taken off reveals what appears to be a dial of some sort that one would use a screw driver to turn.

any help and/or suggestion would be greatly appreciated.