How to access zoom options, e.g. to turn the mouse zooming on/off ?

From Plot->Layout->Edit..., select the General tag, then select the Zoom tag as shown below.

The mouse zooming is allowed if the  check box is checked. Note that if the  check box is checked, the zooming is done in steps; this is a nice visual effect, but is not recommended on a slow PC. The  determines the minimum size of the rectangle drawn by the mouse to obtain zooming (if the rectangle is smaller, no zooming will be performed). The  buttons can be used to display the zoom rectangle area in different styles and colors.