I can imagine how convenient it must be to have an option to view all sales receipts and check if it was paid in QuickBooks Online (QBO).
At this time, the option to check if the sales receipts are paid is unavailable in QBO. You can directly contact the customer to confirm the payment.
Since this was set as a recurring transaction, QBO automatically marked it as paid. If this is linked to a customer's payment method (like a credit card), QBO attempts to charge that method on the scheduled date. If successful, the sales receipt is marked as paid without requiring manual intervention.
With this, I recommend contacting our QuickBooks Payments Support Team to check if there are options to view paid and unpaid sales receipts.
You can also check these articles regarding customizing your sales receipts and other forms in QBO: Customize invoices, estimates, and sales receipts in QuickBooks Online.
Furthermore, you can read this article to learn how to give discount percentages or set discounts on fixed prices and attach them to your line items: Add a discount to an invoice or sales receipt in QuickBooks Online.
Please know that you're always welcome to post a reply in this thread if you have any other questions about sales receipts. I'll be here ready to assist you. Have a great day ahead!