This function has a setting on the Admin Dashboard it is located on
Dashboard->settings->general->User Settings
You can choose between
Fname, Lname
Username
Username (Fname Lname)
Username (Fname)
The way this function works, if you change that setting on the dashboard,
echoUser will change how it displays usernames everywhere that function is called on your site
Example outputs would be
Dan Hoover [Fname Lname]
Admin [Username]
Admin (Dan Hoover) [Username (Fname Lname)]
Admin (Dan) [Username (Fname)]