raise or lower my pressure to what? I use a CHIN STRAP.

My sleep study titration did not use a chin strap. I have a large square head so my chin strap works great. My minimum pressure i set at 15. Ahi is 7. Sleep study titration was set to 12.5
And I was getting ahi of between 3 to 5 without a chin strap. So using a strap should make me put my pressure at what ? I would assume a strap would make me want to lower it. Anyways. Please I need suggestions. I'm basically brain dead. I feel like that anyways. I appreciate ur help. Its hard for me to see obvious common sense.
And without my auto cpap my pressure normally drops in the 60's range. Just adding that so u all know my severity.

I use a full face mask.

Please go to your profile and fill in your equipment in the appropriate section. What equipment you have makes a big difference in what your options are.

A soft cervical collar will likely do a better job for you than a chin strap. If you are breathing through your mouth while using the FFM, the chin strap will increase the probability of obstructive events by moving the jaw a little backward.
The soft cervical collar, on the other hand, just supports the jaw and thereby minimizes leaks caused by the jaw dropping down as your facial muscles relax during sleep.

By soft, I mean really soft and not the stiff kind that EMS use to stabilize the cervical spine. I get my from Amazon.