Question about my pin sight on my new pse compound bow please help?

i just got a pse bow and and it came with a pin sight but it only has one 1 pin, the guy said its supposed to be on at 30 yards. thing is its shooting all over the place, should i get rid of this sight and get a 4 pin sight? and if i bought it at a archery dealer would they sight it in for me? sorry for all the questions im very new to bow hunting.