It is supposed to be lower, common mistake some make is not allowing your hips to hold some of the weight of the airpack. My should straps are fairly loose and my waist strap is snug. Thus lowering the airpack on your torso
I've had this problem myself a few times, you will have to lower it but not so low it wears out your shoulders, but low enough it gives your head more movement... you will more than likely never get full head movement but this will increase it some...
Exactly! The newer SCBA and Sott packs are designed to sit the weight on your hips and not your shoulders. Therefore, your back does not get tired out and not back aches. Tighten your waist and then loosen up the shoulder straps...but not to loose they fall off your shoulder.