Hello Wat,
It appears when we change your easy discuss theme to 'timeless' in your Joomla backend shown here in this screenshot
http://screencast.com/t/0FspjDt5sPrU the edit button appears shown here in this screenshot
http://screencast.com/t/yWh5WwPis .
There may be an issue regarding the compatibility of the old theme you are using which is called zinc in the new update. You may change to other theme in order to make the edit button appear in replies
Regards
Kheng Wei