You'll need to manually create a new customer account and make the existing account inactive, Yvonne.
Duplicating a customer account isn't an option in QuickBooks Online (QBO). On the other hand, you can merge customer accounts to combine two profiles into one.
Please note that this process removes one profile and transfers the existing transactions to the profile you want to keep. For further guidelines, I recommend visiting this page: Merge duplicate customers in QuickBooks.