@mslphd56
"Want to post a journal entry to move cash from checking to a liability account. Crediting the checking acct GL, but wont debiting the liability acct GL make it go down?"
Yes, the liability balance will go down paying-off the debt/liability. For example, you owe $1,000 and paid $400, your balance is $600 now. That's what debiting the liability is suppose to do, right?
You don't post a Journal Entry. It may be a bit confusing for many QBO users.
Instead of using Journal Entry, you may want to TRANSFER option in QBO.
(From the "+ New" > Select Other > Select Transfer (write above Journal Entry, in fact). This one is very simpler to use. You don't need to know debit and credit. It's simple Transfer Funds From Cash account To liability account from the list you want.
Hope this helps!