Press the Next button in the top-right corner and tap Add Action. Search for Set Orientation Lock and tap it. If you’ve done this correctly, you’ll see Toggle orientation lock on screen.

Then tap the Portrait Orientation Lock button (a padlock with an arrow around it) to ensure it’s off—it will display in red if on and locked. On the left, you can see that this phone is locked ...

Then tap the Portrait Orientation Lock button (a padlock with an arrow around it) to ensure it's off—it will display in red if on and locked.

That’s the screen lock function. Tap it to unlock the screen orientation. At the top of the screen, you will now see the message Portrait Orientation Lock: Off.