I have looked through past posts on this and can't seem to get this changed. I've grep'd through the /opt/zimbra/jetty/webapps/zimbra directory for "Username:" and changed everything I can find and I still get the Username: text. I am running the latest NE on Ubuntu.
Consequently, I was able to change the colors via the beach skin and Zimbra logo. Just having trouble changing the text on the login screen.