Are you talking portrait vs. landscape, i.e. vertical vs. horizontal shots?
There's a rather odd swiping of the screen from right to left that doesn't seem to always work but after a few tries does indeed do that and has a button for the change in orientation. I believe you need to be in the camera (not video) mode.
^^ This is how I remember it, I don't use it often, if that's not exactly correct it should get you in the neighborhood.