I'm using the same mask, but I had a heck of a time with leaks at first. This probably has something to do with the fact that I basically have no teeth left. Anyway, after a lot of experimentation I finally got it to work for me by mounting it high on my face, so that the bottom bit of silicon basically sits right on my upper lip and the top is just below my eyes. I have to pull the top bit out to get a good seal, and I have to cinch it down pretty tight, but I have gotten used to it and it's been quite a while now since I had to deal with large leaks.
If I wear it lower the top of the mask restricts my nasal passages and makes it hard to nose breath.
I think I might look at changing to nasal pillows sometime. I went to a full face mask because I have sinus problems and was worried I couldn't get enough air that way. This however seems to have resolved itself after I started using Beclomethazone spray twice a day, and I am mostly nose breathing when I sleep now.
The above is my opinion. It is just possible that I may, occasionally, be mistaken.
I am neither a Doctor, nor any other kind of medical professional.
Everything put together sooner or later falls apart.
Your brain is not the boss.