Selena Gomez's official YouTube account is SelGomez.
Niall Horan does not have his own official YouTube account at this time. However, his band One Direction has an official YouTube account (see related links below).
An official fan YouTube account is not available for Jamie Lynn Spears at this time.
selselgomez
Nick Jonas official account is theofficialnickjj the same thing for twitter
Demi Lovato's YouTube account is therealdemilovato
CodySimpsonMusic. atcodysimpsonmusic
alexanderludwigTV that's Alexander Ludwig's official youtube account for fans!
http://www.youtube.com/user/TheCDPRODUCK253
demi: therealdemilovato
The link is posted below.
Search on youtube for modern combat. you will find their official youtube account.