There are two ways to search for customer accounts in your control panel. In both cases, you will want to ensure that you're in the Billing system. To do this, login to your control panel and select the Billing link in the top right corner.
You'll see a large search box. Select Accounts and then enter your search criteria.
An alternative method is to select Customers from the left menu.
If required, select Show Search to show the search fields.
You can now enter your search criteria as required.