The V-Groove Exterior Backup controls where the Blade Plunges into the Matboard (not the Fallout) on the Exterior Cuts of the Outside Cut of the V-Groove.
The Exterior Cut is where the Blade Plunges/Retracts from the Matboard (not the Fallout).
If the Exterior Backup on the Outside Cut of the V-Groove is cut Too Long, Decrease the Exterior Backup.
If the Exterior Backup on the Outside Cut of the V-Groove is cut Too Short, Increase the Exterior Backup.
How to Adjust the Configurations
When adjusting Configurations, click the Plus(Increase) or Minus (Decrease) button on the desired field about five times.
Click OK and do another test cut.
Continue making adjustments until the desired outcome is achieved.