These directions seem to work right up to the point where you select "Schedule Payments," at which point you get the following error message:

"We're working on it ... Currently online payments can't apply vendor credits or carry over partial payment amounts."

Quickbooks Online is the MOST frustrating program I have ever used. The desktop version is much more robust and user friendly, but for some reason they are pushing everyone to use the online version, which truly is lacking in every single way.