Changing any text on any visible page or email
You can change any user visible text string by updating the Locale in Admin → Locales. You can also add more languages there. Please see: Locale Exchange for more information on adding languages.
To change any of the emails sent by LiquidFiles, please go to Admin → Email template. The layout template contains the overall layout for the email, the API template contains the API/plugin responses and each of the other templates has the contents of all the other emails that LiquidFiles will send.