How to mute sounds in movieclips but not make them play again.

I was tweaking a game I reskinned back in 2020 and I wanted to add screen that showed the credits. I learned little bits of code and I was able to make the credits scene appear on frame 2 of the stage and the music stops. The problem is that the game itself is one big movieclip made out of little clips and when I clicked the go back button to back to the game,  the first instance of the song plays back and a new instance of the song plays, and it sounds all wrong. Is there a way to fix this?

Here's a link to download the game. 

https://www.mediafire.com/file/4szupyjzcvus4r9/CartRider3.1.fla/file