The suggestion of your CPA is also correct, Fannyandtono.

When receiving the deposit, ensure to select the account associated with the service/item that you've paid. You can add notes on the deposit for easy tracking on the Profit and Loss report. This process also helps you to apply the payment on your customer's next invoice.

As for the bad debt, you can create a Checking account affecting an Accounts Receivable account to offset the available credit. Also, it would be best to get in touch with your accountant for further guidance and for the correct way to link the deposit and the invoice with the credit memo.

Here's a reference on how we can write off bad debt: Write off bad debt in QuickBooks Desktop.

Keep me posted if there's anything that I can help. Keep safe!