I understand the importance of undoing payment and vendor credit to the wrong bill in QuickBooks Online (QBO), flipflop. I'd be glad to show you how.
We can undo the payment and vendor credit by opening the wrong bill. Here's how:
- Go to Expenses, then select Bills.
- Click on the Paid tab and select the Bills.
- Select the link (1 payment made).

4. Click on More and select Delete. 
To undo a vendor credit that was applied to the wrong bill:
1. Go to the Expenses tab and select Vendors.
2. Select the name of the Vendor.
3. Find the bill that the vendor credit was incorrectly applied to.
4. Click on the bill to open it.
5. Locate the vendor credit that was applied incorrectly and click on it to open the transaction.
6. Click on More and then select Delete to remove the vendor credit from the bill.
After undoing the payment or vendor credit, you can reapply it to the correct bill.
I've added this article that provides information about managing business expenses and your cash flow through proper bookkeeping practices: Expenses and vendors.
If you have any other concerns or questions about managing your vendor transactions, don’t hesitate to let me know. I’ll be here. Take care always!