Hello there, Sophie4.

It would be my pleasure to answer any questions you may have about the QuickBooks Online Simple Start version.

Creating vendor credits is only available in the Essentials and Plus version. As a workaround, you can use the Bank Deposit feature to record the refund.

I also encourage you to seek an expert's advice from an accountant to ensure your books are correct. They can assist you with choosing the right accounts for the transactions.

In case you want to explore the other versions, you can try our sample company test drive. The article I'm adding below will route you to the QuickBooks URLs:

How to Test Drive QuickBooks Online.

Please let me know if there's anything else I can do for you, the Community will always have your back.