Welcome and thank you for joining the thread, @nancymaria2020.

You can either leave the previous transactions as is or update them depending on how you want to see the transactions. As mentioned by Michell-Long CPA, you have to enter a sales receipt, invoices, or receive payment if you want to view the transactions under the Customer Center.

To learn more about the different accounts receivable workflows in QuickBooks Desktop, you can check this article: Accounts Receivable workflows in QuickBooks Desktop.

Reach out to me if you have any other questions as I'm always here to help. Wishing you a good one!