Hi there, kayarla.
I see that you're not able to stop the Music application on your iPhone from shuffling the songs you've selected to play. Being a huge musical fan myself, I prefer listening to the soundtrack in order as well and I'm happy to help.
Play, repeat, and shuffle music
When playing music on your iOS device or Android phone, a player appears at the bottom or lower-right corner of the screen. Tap the player to open Now Playing. From the Now Playing screen, you can control playback or volume, turn on shuffle or repeat, download the song, and more.Shuffle songs
Open the Now Playing screen and scroll down.
Tap to set Music to always shuffle a list of songs selected. Any album, playlist, or set of songs will play in a random order.
If shuffle is on, you'll see . To turn it off, tap the button until you see .