This page of the guide to Final Fantasy 7 Remake includes The Power of Music side mission walkthrough available in Chapter 14 - In Search of Hope.
You will be assigned with this task by Betty. The little girl wants to comfort people with the help of music. Start by talking to nearby sad residents. They will give you a clue about the music that will cheer them up.
This minigame is very similar to Burning Thighs. But it's is a little more difficult. However, we're about to explain everything exactly to make your task easier.
Start by finding all three records ("Goodnight, Until Tomorrow", " Fight on!", "Stand up"), and then play them to make people feel better. The first record can be found in the hotel lobby at the entrance to The Wall Market.
"Fight On!"you'll find it in the Colosseum. You have to buy it for 50 Gil.
The last song is located near the Honeybee Inn. There's a woman waiting there listening to "Stand up". When you talk to her, she'll give you a copy of the song.
Once you get all three songs, go back to Betty and the jukebox. Play every song you've collected to cheer up the locals and complete the mission.
Reward: Companion Sharpshooter Vol. III.