As Enterprise Portal Administrator, Sign In > Organization > Settings > General > Summary. Change the text to what you want to display. This changes the text ABOVE the screen capture you included. Don't think you can easily change the lower part.
Thanks for the feedback.
I'm trying to give our mobile users an example with how to type there username.
Within our environment the summary does not appear on the iOS login screens while accessing AGE. The summary does appear when our desktop users login.