In the bottom left-hand corner of each view there is the View Caption, that displays the view name ('Top' in this case) and its current zoom factor ('0.66').
Click on the View Caption for the bottom view.
In the menu that appears click Isometric.

The model will now be displayed in an Isometric orientation in the bottom view.
Click anywhere in the top view. Notice how its
view caption becomes darker in colour (and the caption for the bottom
view becomes lighter).
This indicates that the top view is active, so any zooming you do (for
example) will be in this window. (You will be zooming in a later page.)