Hello there, @Dvorak24.
When creating a journal entry, we need to make sure that the income/sales account used is the same as the income account of the sample product. Also, the amount will be the same as the invoice's sales amount.
To check, we can go to the invoice where the sample is created. Then, go to Transaction Journal.
You can refer to this resource for guidance with running financial reports and getting the details you need. It also has report features you may use moving forward: Run reports in QuickBooks Online.
Get back to me if there’s anything else I can help you with. I’ll be more than happy to assist you. Have a great day.