Allow me to share some information on how closing dates affects new invoices.
How you handle new invoices dated before closing dates depends on the accounting method used in QuickBooks Online (QBO).
The Accrual method uses the invoice date. Thus, if the invoice date is dated before the closing date, then the amount on the report will not change even if you pay it after the closing date. The Cash method on the other hand, uses the payment date. When you run the report using this method, invoices will not show unless they are already paid.