Topmusicanswers
There's a toggle button if you scroll down in settings that lets you change the key without transposing existing tracks.
Can you change key in GarageBand?
Each project has a key, which defines the central note to which the other notes relate. By default, new projects are in the key of C major. You can choose a new key when you create a project, and change it later while you're working.
How do I transpose a key in GarageBand?
You can transpose a track in your project by going to the menu bar Track > Show Transposition Track. Transposing means to change the pitch, or pitches of your track into another key. If your song was recorded in the key of A and you would like to transpose it to the key of C, you would use transpose +4 to that key.
