Don't hesitate to comment below in case you need more guidance with handling A/P in QuickBooks Online. I'm here to back you up as soon as I can. Keep safe always!
"Negative days in aging on payables indicate data entry errors caused by two things:
-An accounts payable or accounts receivable transaction has affected the balance sheet account -There's an unapplied payment"
Yikes! Have you even used QB? Those answers are incorrect and you're creating more work for your customer. Does anyone at Intuit screen these responses?