Such documentation as I've found is here: More
There are tabs, or a pulldown menu of tabs, depending on your screen orientation. Tapping "batt cell" (I think that's it) will switch to the cell voltage display. If it says "PURCHASE" in the corner, you're looking at a demo screen and need to buy the upgrade for a dollar. Cell voltages change A LOT so only expect consistency/reliability when the car is on, but parked for a minute or two, and engine has turned itself off. Fresh off a charger will show you how well the balancing has worked (cells should be very close together in the min/max read out at the bottom, but will hide weak cells from you. Doing a reading when the battery has been discharged and the car has switched to engine at least once will show weak cells if there are any, and you'll see a bigger deviation between the min and max in mV.