How do I keep my Samsung Surface 3 from constantly shifting from portrait to landscape?

[antfaber]

When I try to use my tablet while lying down, it constantly shifts from landscape to portrait and I'd like it to stop doing that. I figure that disabling Smart Screen is the way to go, but I can't find where to do so.

 

[B. Diddy]

Welcome to Android Central! Samsung Surface 3? Man, Microsoft must really be branching out! I assume you mean your Galaxy Tab 3, correct? There should be an Auto-Rotate toggle in the Quick Settings: Samsung Galaxy Tab 3 User Guide

 

[antfaber]

Thanks. That fixed it.