Choosing which way to correct? – Expert FDC Review

I downloaded this app after a recommendation and after a day of playing with it along with a board it seems to be accurate. The only problem is that there is no way to specify a specific direction for the corrections i.e. Left/Right, Add/Drop. I have tried using +/-signs but those don't seem to work as thought.
Review by Asukid11 on Expert FDC.