Most buyers who buy an Android TV box just want to use it to watch videos, browse the web, play games, and so on, so landscape mode seems to be the best choice, and orientation option in the firmware is often disabled. However, TV boxes can also potentially be used as digital signage players, which may require landscape or portrait modes if the screen is positioned vertically. Since I’ve just been asked that question, I’ve checked for a solution, and luckily there’s an app called Set Orientation that does the job.
When you first start the app, it will show the option “Disabled”, but you can click on the arrow to reveal more options, and select Portrait to rotate the screen.
In case the screen is upside down, simply select Portrait (reverse) option, click OK, and you’re done! Easy.