Zombie Survival Last Human Song

how do i change Last Human song? i tried changing it in gamemode/zombiesurvival/content/sound and putting a song there and renaming it to lasthuman.mp3 and old lasthuman song to lasthumanoriginal.mp3 and i still hear the old song… what do i do? please help

Edit:
i went into sh_options and changed lasthuman.mp3 to believe.mp3 and in gamemode/zombiesurvival/content/sound i had believe.mp3 and still doesnt work

Your client probably still has the old file and is loading that one. xD