The usual is the awning has moved on the roller or at the wall due to the wind. I used to get on a ladder, lift the roller to get some slack and try to wrestle the awning back to where it rolls up straight. Which way to get it straight you ask? I forget exactly.
There are previous Posts on this but I think (be careful here) that you can see where the awning doesn't roll up straight. Move the awning, on the roller towards the direction it is rolling (make sense?). Once adjusted, use a Sharpie to mark where the ends should be in case it moves again.
A better solution was shown to me in Lake Havasu by the Shade Pro awning installer. Slide the awning in the channel attached to the body of the RV. It slides pretty easily. Roll the awning in and out to check, and then adjust as necessary. Once it is aligned, run a small Tek screw through the binding and the channel on each end to keep it from moving again.
Lastly, for a small offset of 1/8" I just lean on the arm while it is being retracted.