I'm looking to change the definition of "COM_VIRTUEMART_ASK_QUESTION_THANK_YOU". Can this be done inside Joomla, or do I manually have to edit a .php file? If so, please direct me to the right file.
they are standard Joomla lang constants .. use the normal Joomla lang over ride system
See the FAQ: http://forum.virtuemart.net/index.php?topic=113895.0