RESMED Liberty and Quattro

I have both of these but prefer the Liberty as it doesn't go over my nose and so no soreness on the bridge of the nose BUT>>> How tight to people put the straps and what trick/method do you use to check and adjust the tighhtness?
I found that allowing it to be reasonably loose so that the cushion could fully inflate like a hovercraft's skirt meant it moved easily and leaked, just like a hovercraft. If I tightened it then it might leak from the sides as I changed positiion and if over tight it wouldn't seal at all. I can't seem to get a good fit repeatedly and each night it's trial and error which starts to frustrate me and so my calm sleep mood goes out the window.
I think it's a great mask but want to get it right without becoming frustrated.
Secondly can the same principles be applied to the Quattro just in case I need to swap. I understand the clips on the Liberty are rather fragile.

Thanks in anticipation

Jono