@thommyb sagte in Schedule update: Choose the key of a song every time it's used:
Yes, that would be my answer too, except ... CT doesn't print the arrangement or display it in the app, unfortunately!...
But it "chooses" the right arrangement automatically when you press in the song (either via the plan or the song list).
So confusion only occurs when you want to communicate with "non-CT-people". 😉