wiper blades not in sync how to adjust bolt?
 

My 2002 caravan had heavy snow on the blades in the morning and the wiper blades (under the weight) got screwed up and they are now out of sync.
Initially they were flapping against each , until I was able to turn them off, unpopped the black plastic shield at the base of each arm, and then with a crescent wrench proceeded to try and adjust the nut as they were turning, then when they were turned off, and they got totally screwed up.,
Now they only move just a smidgen and then down again.. What is the secret to the adjusting? Should they be up or down to start? should the nut be tight or loose?
any help would be great , as I fear it will be raining soon...
Thanks