You remember correctly, according to pages beginning at 179 in your COMAND manual. That should occur in the route guidance mode. However, I believe it only occurs if you have set the nav display to show turns (as the instrument cluster display does); if you have set it to show only the map, with turn diagrams only on the instrument cluster display, I don't believe you get the street name you're turning to at the top of the COMAND screen.
Selecting the "mix" display that switches to the turn diagram automatically is at page 196. I don't have time now to research it more for other settings; an electronic version of your COMAND manual is at
http://phdwebsite.powerpulse.cc/COMA...L%20COMAND.pdf if you no longer have the printed one.