thank you for your reply,

I did put the settings at 100 again, save it, reboot (while headset plugged all time), but it did go back at 88 on every reboot,

maybe there's something wrong when I save it? I installed the root thing, and before doing stuff, I used the sudo gainroot command...

(I have to say it is really frustrating, because there is a way and you can see the nice result of it ahah)