Sandra,
I had this problem with the Resmed Swift (and I was using the biggest pillows

) This is what worked for me.
Try using your old pillows and with your machine on and the pillows in, pinch your nose until the leaking stops. Then slowly relieve the pressure on your nose. This will allow the pillows to seat in your nose. I think the air escaping around the pillows flares your nostrels and doesn't allow the pillows to seal.
Good luck!