As mentioned a light coat of Lansinoh cream applied to the nostrils about half an hour before going to bed will help the pillows seal.
I also roll a cotton ball and insert it between the pillows so they won't collapse inward and tie one of my wife's knee highs around my head and across the pillows to keep them from popponig out the side. Works very well for me; have used this fix for over a year.
Hope this helps.
Don