Magento “Thank you for your purchase!” page & how to edit it
If you want to edit / customise the Magento page that says “Thank you for your purchase!” after an order is placed but can’t find it then read on.
The page you need is the SUCCESS PAGE and the template file for it is: success.phtml.
If you can’t find the file within your theme, then it may not exist and your site is using the default base file.
The path where this file is located is: /app/design/frontend/base/default/template/checkout/success.phtml.
Copy this file to your Magento theme and edit it.