1st and 2nd choice of majors in totally different field

I know for some schools i can choose one major as 1st choice and something else as 2nd choice.

I really want to do something related to music in the future, but using technology.
so i was thinking of comp sci as my first choice,
but if that does not work out,
vocal music as my second choice.
I’m going to write about how I’m going to imply comp sci in the music in application.

However, i thought it would be possible for them to think that i “just” want to get into this school in any way because its totally different field…

if i apply for the major like above (comp sci 1st / vocal music 2nd)
would they think that i dont care about what i do? especially USC