Hey Pap87 !
Try using a Gravity and a Damp Force. The “gravity” will of course place your hair back down, and the “damp” will slow down the velocity of each hair.
But if you really want the hair not to move then use the “Static” option on you hairSystem node.
I hope that helps!
You you have a screenhots of what the hair looks like whenb it’s messy like you said, it would help me diagnose the issue