That happens when you are currently viewing the world from the top-down view, which is what you get when you start, or when you reset-perspective.
Instead, if you orbit-down 90 first (either with code, or with the mouse), then when you orbit-left you will spin around the scene, instead of the "lazy susan" view.
However, if you've already written all your code based on the X-Y view, you may have to change a fair number of things to make it appear the same way in the X-Z or Y-Z view. For example, you may need to start your turtles at low zcor instead of low ycor, to be at the bottom of the screen.