How to located front end "Written By" of "Author Alias" in Joomla

When I set the standart or custom "Author Alias" in a Joomla article, it is on the front end website preceeded by the words "Written By".

I am however using the "Author Alias" field for a different lable, and need to change the "Written By" description to something else.

Could somebody guide me to the right place where I could replace it. I have tried searching phpMyAdmin and the template, but no success!

Thanks for your help guys!