I freaked out a bit when I tried the tutorial section # 9.
QuoteZoom into the Mid-Level map using any method. The default is unit type. To select a different display attribute, mouse right click and select "Display Attribute Selection". WWIIE will display a list of attributes (note WWIIE highlights the attributes as you move the cursor over the name), and then mouse left click on the name of the attribute. WWIIE will display that attribute on the units in the map area.
What I found I had to do was use the mouse button "Display all units using unit type attribute". There should be a option like this in the "Display Attribute Selection" dialog that pops up.