You can customize the "Thank You" emails that customers receive after they buy your product. To do so, go to your Product's edit page and open the Advanced tab. When you enter in your message, be sure to save your settings.
To do so, go to your Product's edit page and open the Advanced tab. Enter your message. If you have translated versions of your message, click Add translations, choose your language, and enter in the translated version of your message.
Be sure to save your settings. Make sure you’ve enabled translations in your site settings in order for this to work.