The page orientation in OneNote Online cannot be changed. To change the page orientation, switch to OneNote for Windows 10.

1. Check your platform. Determine if you are using OneNote Online or OneNote for Windows 10.
2. Switch platforms. If you are using OneNote Online, switch to OneNote for Windows 10 to access custom page orientation settings.
3. Adjust the page orientation. Once in OneNote for Windows 10, customize your page orientation settings.