None of these options work. I am having the same problem. I went in and changed my settings to automatically apply credits, but it won't apply them to existing invoices. I am on hold with customer service, looking at 30 minute wait. I've tried every logical option to apply this credit. I need to apply it and then send the invoice to the tenant/customer so they can see what they owe. It appears they will need to pay the balance due and then I would be able to apply the credit, which makes no sense and is cumbersome. I rarely issue credits and don't recall this problem, so it may just be a glitch since I've searched online quite a bit and the typical instructions do not work.