I need a bit of help.
A short passage in a piece for “French horn in F” is written in C sharp major (7 accidentals). However, I can’t seem to enter 7 accidentals. Dorico always automatically changes C sharp major to D flat major (5b).
I think you’re talking about the key of concert F#, which should be C# in the transposed horn part but which Dorico displays as Db. In this case, you can go to Notation Options > Accidentals > Transposition and untick this option: