[Zubersoft]

The dropdown option on the dialog is indicating what display mode to use in each orientation. By switching that to portrait, you can just pick a different display mode when your tablet is in the portrait orientation. If you closed that dialog, rotated your device, and then viewed the dialog, you would see that it switches the dropdown to portrait automatically so that the user is seeing the display mode for the current orientation. If you want to rotate your pages, tap the display settings icon at the bottom left (it looks like a gallery icon), then tap on "Rotate". You can then rotate either the current page, all pages in the current file, or all pages in the entire song (if you long press the rotate icons without a number in them).

Mike