Hello and welcome Karin,

I had the same problem when I began playing and tried all manner of picks, pressures, way to hold etc. I finally settled on some favorite picks that I keep in my pocket holder. Lots of regular practice has accustomed me to the pick moving around but it is no longer a problem. Its like driving a car, we get used to making mirco adjustments without thinking about it.

In terms of pressure, I just picked up my guitar to see what I do. Well, the pressure varies. For the most part my pressure is fairly light, but when I strummed through a few AC DC chords I had a pretty firm grip on the pick. So I guess it comes down to what I am playing at the time. And something else just showed through, I change the way I hold the pick, again it seems to depend on what I am playing.

Best of luck with your studies