This screen will only allow you to amend the Customer details but NOT the Customer Name. 

Sales > Add/Amend Customers

Select the Customer name from the drop-down list that you wish to change by clicking on the down arrow to scroll through the list of Customers which is sorted alphabetically.

You may amend any of the following details within this screen:

• Customer Address
• Customer Contact
• Customer Telephone Number
• Customer Fax/Email
• Any comment linked to the Customer Account
• Click "Update" to save the amendments