My Apple device plays the same song over and over. How do I change that?

Welcome to the Apple Support Communities!

I understand you have one song repeating itself on your iPhone 6s. Take a look at the resources below for playing content in the Music app. I've highlighted some key information here for you. Click on the link for complete details.

Play, repeat, and shuffle music
Open Now Playing on your iPhone, iPad, iPod touch, or Android phone
When you play music in the Music app on your iPhone, iPad, or iPod touch, or in the Apple Music app on your Android phone, a player appears at the bottom or lower-right corner of the screen.
Tap the player to open the Now Playing screen. From there, you can play a song, control the song's volume, share a song, turn on shuffle, set repeat, and more.

Repeat songs

Open the Now Playing screen and scroll down.

Tap once to turn on repeat for an entire playlist or album. Tap again to turn on repeat for one song. Tap a third time to clear the repeat.

When repeat is on, you'll see or . To turn it off, tap the button until you see .

iPhone User Guide - Play music
Take care.