After you hitch to the trailer coupler, raise both trailer and tow vehicle high with the tongue jack. If you raise it high enough you'll never need to use a cheater bar. You may have to put blocks under the tongue jack before you start so the tongue jack will raise high enough.
When unhitching, do the same thing. Raise the tongue jack high lifting both tow vehicle and trailer, and bars (and in your case, the chains which which catch on that snap up device), come right off with no force or effort at all. Once off, then lower and finish unhitching.
The higher you jack up the tongue, the easier they install-remove.