How to scroll the plot using the mouse?

If your mouse has a wheel, you may use this wheel to scroll vertically.

Clicking the right mouse button and dragging will scroll the plot.

The direction of scrolling can be set. Under Plot->Layout->Edit..., select the General tag, then select the Scroll tag, then mouse zooming can be set from the Allow Scroll radio buttons shown below.

You may also select what mouse button to be used for the scrolling as seen above.