On the Autofill Student Information page there is a Priority field for each grade level. The lower the number the higher the priority for scheduling. Our team usually fills the Grade 12 Priority as 10, Grade 11 as 20, etc.
Also if AP Pysch is a priority for the school you can give any course a higher priority number as well. We do that with a couple of are singletons that are harder to schedule.
In PowerScheduler - Courses there is a LOAD PRIORITY near the bottom of the screen for each class.