The first dropdown controls how the opponent’s moves are chosen during training.
Random – Moves are chosen at random. There is no guarantee that you’ll cover everything in the tree of analysis but facing random candidate moves is harder and more realistic.
Random with coverage – Moves are chosen at random but the wizard will move on to other moves so that eventually you will cover all the variations.
Sequential with coverage – This is the default setting. The training wizard will play the first candidate move in each position and then the second candidate move in each position, working its way back through the tree of variations until the entire tree has been covered.