When working with scores in keys of four sharps or more, it’s frequently desirable for transposing instruments such as Bb Clarinet or Trumpet to show their respective transpositions in flat keys. For instance, the key of B major concert (five sharps) will automatically display in Finale’s Clarinet or Bb Trumpet staves as the key of Db (5 flats), rather than C# major (7 sharps).
This desirable behavior happens because in the Transposition Definition for these instruments, “Simplify Key” is checked by default:
Finale’s rule for “Simplify Key” is: always show the enharmonic key signature which displays the fewest accidentals when transposed. For concert keys of five sharps or more, Bb transposing instruments will always show flat keys (which, coincidentally, many wind and brass players prefer).
However, you may have noticed that “Simplify Key” doesn’t work in four sharps concert, because, technically, the two possible enharmonic key signatures of six sharps or six flats, are equally “simple”.
That being the case, how can we coax a concert key signature of four sharps (E major or C# minor) to appear as six flats (rather than six sharps) for Bb instruments?
more >> “Finale : Six of One ; ½ Dozen of the other – the Simplify Key Conundrum”