Hi Dennis... welcome!
Need a bit more info...
Did you get a copy of your
sleep study? Posting that info might help here to a degree... specifically, the
titration part of the study would show what pressure setting(s) were recommended... that would be a start.
Also, I would recommend you get a free copy of
ResScan (directions on how to get it
here in the Private Files & Links Forum). You can monitor your AHI, pressure and other data with it easily - you just need a cheap $20
SD card reader for your PC.
Your machine is currently operating in "Wide open" mode (4-20 cmH2O of pressure), and while this might be a good starting place, generally-speaking, a more narrow range of pressures (customized and
optimized to minimize your AHI levels) is much better.
The two things you're going to be interested in is your average
AHI levels and also your CPAP's 95% pressure levels. Once you post those, we can help you with more specifics.
Here's an info page about your ResMed S9 AutoSet CPAP machine that will help you (includes video):
http://www.apneaboard.com/resmed-s9-cpap-setup
Also, is there any reason as to why you're using a Full Face Mask? They are notorious for leaking and if you can in any way tolerate a standard nasal mask or nasal pillows system, those are going to be a far better choice for you in the long run.