I put "hack" in quotes, because that would be rather generous. But anyway, the straps on the Daylight Backpack were never quite the right angle for me, because it's a webbing strap with no curvature, so it can't wrap around in the snaky way a real strap would. But you can just do this:
It seems to stay in place just fine, and it completely changes the angle both up at the shoulders (making it a steeper angle, which is good for sloping shoulders), and the lower part seems to get further away from your arm, so it doesn't dig in as much. It all looks a bit silly, but I bet it would look nice if it were "officially" sewn down that way.