The View button in the bottom left hand corner of the Frame, Load and Plot windows can be used to display a range of two and three-dimensional views of a structure.  Each window has its own view and is controlled separately by its view button.

You can change the view by clicking on the View button and then clicking on the icon of the view you require. You can also change the view by using the View3D toolbar.

The view may also be changed via the Current View submenu in the View menu.