How do I change my view of the set?

At the start of every fresh scene, you are positioned like a celestial Director of Photography, behind and above the camera.

As you make the set more complex, you may find the need to move around to see behind your characters or into the little nooks and crannies you have created.

To do this, set the screen to 3D mode by switching the toggle in the bottom right.

Then place two fingers in the center of the screen.  Hold them on the screen and spin them, allowing one finger to go above the other.  It's sort of like turning a door knob.  

When your two fingers move away from each other, the view zooms in and when they come together, it zooms out.  

Practicing and utilizing this viewing flexibility will give you much more control and attention to detail in the development of your shots.