I don't doubt they were young and that they were loud and annoying. But they have to be 21 to book a cruise. And to have someone under 21 in your cabin, you have to be a legal guardian, so they were probably older than they acted.
I agree with the security no being proactive. You could call them and complain and it would be an hour (if ever) before they would come and investigate.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise, Magic 1/14
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013