You adjust them however feels comfortable to you. A lot of people will adjust them so that they are parallel to the backside edge. Some adjust them so they are inline with the binding. Do whatever feels comfortable to you.
What do you reccomend? Iv seem a lot of how to's and people say to adjust them parallel. when the yguy set everything up at the shop i bought it from he left them straight with the binding. Should i change it? Im using rome 390 boss btw.