Right out of the owners manual
Arc Adjust Term used to represent arc length adjustments in pulse programs. Increasing Arc Adjust increases
the actual arc length. Likewise, decreasing arc adjust shortens arc length. Arc Adjust is replaced by
volts in MIG programs.
Arc Control Allows setting of inductance and slope in MIG mode. In pulse and Accu-pulse mode, this adjustment
changes the arc characteristics by adjusting the preprogrammed factory pulse data.
I would stay away from "Arc Control" adjustments unless you are having major issues with the factory presets for the program you are running... Which you shouldn't...
Maybe describe your problems with the process up to this point?
Are you running Semi-automatic/Manual or Robotic/Mechanized ?
Edit:
http://www.millerwelds.com/om/o245592d_mil.pdf