Hello there, mahalo111.

Allow me to jump in. Yes, certainly you are right that changing information for a customer account in QuickBooks Online will not affect existing customer sales history as long as the customer name remains unchanged.

Moreover, please note that when importing contacts from a spreadsheet, it is important to ensure that each entry in the Name field is unique. This applies to files exported from Google Sheets, Excel, and CSV formats. It is essential to avoid having multiple vendors, customers, or employees with the same name, as this can cause confusion and errors in your contact list.

You can also check this article to learn how to add, edit, delete, or merge customers in QuickBooks Online: Add and manage customers in QuickBooks Online

Thanks for coming to the Community. I look forward to being able to help you with your concerns about managing your customers in QuickBooks Online. Have a great day.