Are most of these white-outs coming at dusk and dawn? That's when most IR cams have this issue. During the transition from light to dark. The pir setting is the sensitivity control of the sensor. How sensitive the sensor is. Generally it's needs to be higher in the summer because of less difference in the air temp and the body temp of the subject. If you are getting alot of white-out pics in the daytime, the IR filter may be stuck. Hope you get it worked out. Niether the PIR or resolution setting have anything to do with getting white-outs.
Blessings.......Pastorjim