I attached a screenshot to explain what I'm trying to do.

Each transaction has a class.  I enter a bill (and assign a class) but when I PAY the bill out of the checking account, I can't find a way to assign the change of money to a class, so it shows as "uncategorized" on the Statement of Financial Position (what would be the Balance Sheet in for-profit organizations).

How do I ensure that the bill payment correctly gets assigned to a class to avoid it ending up in uncategorized on the cash account?  It's sales, bill payment, basically EVERY transaction ends up in uncategorized no matter what class the individual transactions are assigned to.