How do I link an admin-created order to a customer's existing account?

On Orders → Manage Orders → Create order, use the Customer box in the right-hand panel.

1. Start typing in Search customer…. You can search by name or email.
2. Click the right customer in the list. Their Full name, Email and Phone are filled in for you.
3. Add the Address line 1 and other address details, then click Place Order.

The order is linked to that account, so it appears with their other orders. To start again with a different customer, click Clear.

If you just type a name and email without picking from the list, the order is placed as a guest order.