Okay, here we go. First of all, go to your triggers panel, highlight the hands triggers and press delete to remove the current triggers.

Now go to the rig mode (if you're not there already) and pick an arm to find the hand set - this is the group of hand layers inside the hand group. Make sure you grab the group, not the individual hands.

Drag this group over to the trigger panel and over the "Create Swap Set" button to create a swap set. (The button appears when you're dragging over the panel)

Once that's done, you'll find that you've created a new swap set for that group of hands. All that's left to do is to assign keyboard triggers to each hand in the set. "Latch" means that the hand will stay in place until you press that key again (or press the key for another hand). Without Latch, the trigger only lasts as long as the key is pressed. "Default" means this is the default hand in the set that appears without any prompting.

I hope this helps!