Since I have a keyboard in front of me now, I will elaborate...
Everything you touch when riding, the position of the controls, the width, height and angle of the bars, the seat shape, the seat height, seat firmness, the grip of the plastics for your knees, the height/setback/width of the pegs, etc... are all adjustable.
now the #1 reason for numb hands is deathgrip on the bars. if you are squeezing the bars at all, or if you're using them to hold you on the bike you're riding it wrong. You should be relaxed with a very light grip on the bars, and hold yourself up by your core and lower body.. not the bars. this alone is the issue for most people.
that said, we're all not the same, and maybe its just the wrong angle for you, or you have pinched nerves, or maybe just a specific back muscle gets tight. whatever the case may be, the key is to first identify the problem... THEN solve it... it may mean you have to move the bike to fit you, or it might require you to learn a different riding technique. If you can identify what you want to change, this forum is full of helpful and thoughtful people that will help you find some way to fix your issue.