Adjust the V-Groove Backups and Overcuts to control specifically where the blade plunges in and retracts from the matboard or the fallout when cutting a V-Groove. 

The V-Groove Exterior Backup (green arrow) is where the blade backs up before initially plunging into the matboard on the outside cut of the V-Groove.

The V-Groove Exterior Overcut (red arrow) is where the cut continues into the corner before retracting the blade from the matboard on the outside cut of the V-Groove.

The V-Groove Interior Backup (black arrow) is where the blade backs up before the initially plunging into the fallout on the inside cut of the V-Groove.

The V-Groove Interior Overcut (white arrow) is where the cut continues into the corner before retracting the blade from the fallout on the inside cut of the V-Groove.

The inside of the V-Groove cuts first in a clockwise direction. These are internal cuts, which cut into the V-Groove fallout.

The outside of the V-Groove cuts second in a counter-clockwise direction. These are external cuts, which cut into the matboard.