Set the key signature for a project in Logic Pro for Mac
Each project has a key signature, which defines the central note to which the other notes relate and which notes are flat or sharp. By default, new projects have a key signature of C major. You can choose the key signature when you create a project, and change it later while you’re working. When you add Apple Loops to your project, they match the key signature of the project.
When Enable Complete Features is selected in Logic Pro > Settings > Advanced, you can also add key signature changes in a project. Key signature changes affect the display of MIDI notes in the Score Editor, and they can also affect the playback of MIDI regions or Apple Loops, depending on their Pitch Source setting. See Create key signature changes and Control transposition with the Pitch Source parameter.
Set the project key signature
In Logic Pro, do one of the following:
With the playhead at the start of the project, click the triangle on the right side of the LCD and choose Beats & Project, click the key signature, then choose a key from the pop-up menu.
In the Score Editor, double-click a staff between the clef and time signature, then choose a key in the Key Signature dialog. You can also drag the key signature from the Part box to the beginning of the project.
Click the Create Key Signature button in the Signature List.
When you change from a major key signature to a minor key signature, in some cases the key may change enharmonically (for example, from Db major to C# minor). These changes follow common practice for printed music, and affect only the key signature as shown in the menu, not the pitch of regions in your project.