It's a pleasure to see you here in the Community, @Anonymous.
I can help you process the downloaded payments from your bank against an invoice in QuickBooks Online (QBO).
You can simply match the them to the existing invoice(s) to change their status as paid. Here's how:
1. Go to Baking menu at the left panel, then Baking tab.
2. On the For Review tab, click the downloaded payment.
3. Select Find match, then a match transactions window will open.
4. On the Search field, enter the name or amount, then put a checkmark on the invoice.
5. Click Save.
I also added some sample screenshots below for your guide.
Once done, the transactions you matched are moved from the For Review tab to the In QuickBooks tab. For your reference, you may check out this article and scroll down to record payments for existing bills or invoices for further guidance: How to add and match downloaded banking transactions.
That should do it! Please let me know how it goes by leaving a comment below. I'd be glad to answer if you have any additional questions. Enjoy the rest of the day.