What's the proper way to transpose a piece of music?

I’m working on a composition originally written in A flat major, and want it to be in A major.

First, I transposed each track individually, up one semitone, by going into Midi Modifiers/transpose. That made it sound right but I saw that in Key Edit, when I clicked on what sounded like an A, it was still an Ab. So then, to get the notes to look right in Key Edit, I did a Freeze MIDI modifiers. Everything looked and sounded perfect – until I did a score. I’ve got the right key sig in there for A major but it seems to think it’s still in Ab major so it’s putting sharps and accidentals everywhere.

I am so lost. Was there a more correct way to do this? I am now back to the original file I saved before making this mess, and need to start again. Someone has suggested I first do a transpose in the Score then go back and redo what I did. But before I make it worse, I thought I should check here.

MIDI Modifiers only acts on the MIDI data on playback not the actual data itself.

Open all the MIDI Parts that you want to transpose in the Key Editor.

Select all the MIDI Notes (ctrl+a) and drag them all a half-step up. Or use the up-arrow key to move them.

Thnks Raino. How incredibly simple.I am amazed

Even easier is to select all parts in the project window and use the transpose dialog (cmd T) to enter +1 semitone.