There is a pretty good video at this link explaining how to fit the mask https://www.usa.philips.com/healthcare/ ... -face-mask
I can only get a good seal with my Amara View when I use mask liners. I started with liners from Remzzzs http://remzzzs.com/
Once I got them to work I used one of the liners as a pattern (transferred to a piece of cardboard as a template) and now I make my own liners from old tee shirts.
It does take me several minutes each night with pressure on to finally get the leaks to stop. The Amara view has been the only mask I have been able to stick with. Like the video above says, the intent is to have your mouth partially open. I get leaks if I close my mouth.