I'm quite surprised that you still have customers who choose to pay via check in this ACH, credit card, and e-wallet payment age, midtx.
In this case, we're unable to record the bouncing check if QuickBooks doesn't have the customers' profiles. If you can record this in the third-party app and that info is exported to QuickBooks, you will not need the profiles. QuickBooks will reflect the cash-in and cash-out entries from your app based on payment and bouncing check records.
If you're not able to record this in the app, I would recommend consulting an accountant. You may need to do journal entries to record the loss of sale. They are much more capable of suggesting the best accounts to make sure that your books still follow the standards of accounting.
By the way, here's how we record bounced checks with customer profiles in QBO: How to enter a returned or bounced check using Write Check.
Also, here's the article on how to reconcile an account in QuickBooks Online.
Leave a comment below if you have more clarifications. Have a great day!