After solving how to unhook and hook up, you might check and see if the dealer set the WDH up correctly so that you have adequate weight transferred back onto the steer axle. Also check that bolts/nuts are properly torqued and that the trailer is level to slightly nose down when fully loaded.
Dealers are notorious for messing up WDH installs. There is a great sticky in the towing forum. When we picked up our current TT, the salesman came out with a battery-powered impact driver and was about to tighten the nut on the hitch ball with it. I had taken my torque wrench and sockets with me and told him thanks but no thanks, I've got it.
Raising and lowering the coupler with the tongue jack is normal procedure to hook up & unhook.
