Selecting ‘Traffic’ display range:
On the MFW 'Traffic' page, touch the screen with two fingers and pinch in to increase the range and pinch out to decrease the range.
Or:
Use one finger to slide up and down on the 'Traffic' Page to zoom in and out (sliding up zooms in and sliding down zooms out.
Or:
Turn the Inner DCK clockwise to zoom in and counter-clockwise to zoom out.