As best I can tell, the problems I have are on the sides of the mask, not the top or bottom. I added a strap below my chin, running through the two bottom straps to prevent the mask from riding up, which has worked well. Now I have started using strips of bandage tape on the sides of the mask. I'm using 1" tape and folding it in half, so that one half adheres to the cushion and the other half to my skin. This way, if the mask lifts up, instead of being open, the air will be trapped by the tape. So far it's working, but I've only used it twice.
Between the extra strap and the tape, putting on the mask is getting to be quite a production. The secret of getting a good seal with this mask is supposed to be not over-tightening, so the double walled cushion can fully inflate, but it seems like the shape of my face changes too much when I sleep, and the cushion can't adjust.
So I'm looking for any tips or suggestions which might help. I haven't tried mask liners. Money is a bit tight, and I'm hoping to find a more cost effective solution. The tape might be it, but it's a bit uncomfortable, and I'm having to tighten the straps too much to get it to work.
I've been training myself to nose breathe, and today I ordered an Airfit N10, but even if that works out I still want to make a full face mask work, for times when I'm congested.