How do I make my stage monitor mode appear in portrait instead of landscape?

How do I make my stage monitor mode appear in portrait instead of landscape?

Not only can OnSong be used on your tablet on stage, you can also output chord charts to others using Stage Monitor Mode.  By default, this displays your charts like a music stand with songs being presented side by side on a landscape orientation. To use your TV monitors in portrait mode with OnSong, you will need to perform the following steps.

Screen Mirroring
OnSong controls the output of video allowing it to draw lyrics or charts on the full external display. If you've enabled iOS Screen Mirroring, you'll want to disable that first.  To do this, go into the Utilities Menu by tapping on the gear icon in the Menubar and choose Settings > Live Settings > External Video.  Locate the Screen Mirroring (iOS) option and turn this off.  Tap the Done button to save your changes.  You may also need to restart OnSong.

Enable Stage Monitor Mode
Once reset, open the External Video Menu by tapping on the TV icon in the Menubar and ensure that Stage Monitor Mode is enabled using the Mode Buttons. This is the button on the right underneath the lyrics preview screen that appears like a TV linked to iPad. Please note that Stage Monitor Mode is not available on Chromecast or Google Cast devices.

Configure Settings
Lastly, we need to configure our settings to display the chord chart in portrait orientation. To do this, either tap the wrench icon in the top left of the External Video Menu and choose Stage Monitor > Screen Orientation. Choose either 90º or 270º depending on how your have your display positioned. Then go back and set the Aspect Ratio to match your display. If you're using an HD display, this is most likely 9:16, otherwise it's likely 3:4. Once you're all done, tap the Done button to save the settings and update the external display.