The Viewer Pan Buttons, situated in the Viewport Control Panel, scrolls the viewport in the indicated direction when depressed with the left mouse button. These buttons are not meant for single "clicks", but rather a "hold and release" fashion, until the viewport contents has changed the desired amount.

You will observe that operating one of these buttons causes the viewport graphics to scroll in the opposite direction:

• Left pressing the LEFT pan button pushes the viewport graphics to the right. Just imagine the viewport "floating" over the data, and then the action will become intuitive.
• Right-clicking the LEFT or RIGHT Viewer Pan Buttons will "snap" the graph to the left/right ends of the graph. Right-clicking the UP or DOWN Viewer Pan Buttons has no effect.