Help me with music

can someone tell me what to use when using a shortmusic
we have to use music and music off or sound
coz when i used preview on my phone and i use sound shortmusic_whatever…
It doesn’t work but when i use music shortmusic_whatever… it works but when it ends it starts playing over and over but i only wanna use it for short period .
can someone explain me this ?

if you want it to repeat in loop then choose music but if you want it to be repeated only once then use sound