Here are a few things you can try first to try to fix the OneNote page orientation issue:

1. Check out your Printer preferences to make sure the page orientation for OneNote is set to the correct option.
2. Try previewing the document before printing to make sure it is in the correct orientation.
3. If the issue persists, try to restart the OneNote application.
4. See if it helps if you reinstall or update OneNote.
5. If nothing else works, try disabling your printer or changing the default printer.