Waist Belt Placement

I just got my BCD last weekend, and my instructor fitted it to me, but the waist belt seems kind of high, in that it runs across me just at or slightly above navel level. I am one of those people that have a disproportionately long waist in relation to body height and am thinking that I should lenghten the shoulder strap drop, in order to lower the waist belt. Is there any practical reason for the belt to ride high, or is this an adjustment that should be made to suit the individual?