The standard french horn fingerings are set automatically to the default F fingers. To
change the fingerings say to accomodate the double horn, simply go to the Fingerings screen and change the
default fingerings to Bb or Custom.
Each note from low F to C above the clef can have an alternate fingering. French Horn Pro
doesn't care what fingering you use - you can even use fingerings that would not work on an actual french
horn! Here is where you will change the fingerings if you're interested in practicing double horn fingerings.