We have set up profile synchronization and user are displayed as "FirstName LastName", but client wants to display user name from AD. What do I have to change in user profile service to display user logon name from AD instead of his first and last name?
There is a workaround to this, but I don't recommend this.. May not be the appropriate answer but this should complete your need...
a) In Central Administration under Application Management select Manage service applications
NOTE: You will loose the Name information of the user, if you want to keep it with you - you can create New Property and map it to full name of the user...