However, the process has changed in more recent versions of the mobile operating system.
Tap your account icon at the bottom of the screen to open up the options screen.
Now, tap Spotify to set it as your default music player.

Can You Set Spotify as the Default on an iPhone?
Apple has yet to add an official setting to let you set Spotify as your primary music player.
So, technically, you cannot set Spotify as your default music player on your iPhone.
Activate Siri by holding down the power button or saying, “Hey, Siri.”
Once the assistant activates, ask it, “can you play music using other apps?”
Why Isn’t Siri Giving Me a List of Apps?
Siri may not bring up the list for you if you’ve already used Spotify with the voice assistant.
That’s because changing this setting does not set Spotify as your default music player on iPhone.
Instead, it simply teaches Siri you like to listen to music through Spotify.
To store the tracks locally, launch the playlist, and then select theDown arrownext to the Play button.
The most common reason for Spotify to pause without warning is a bad internet connection.
you’re free to also kickstart your unit or check for an update to the app.
Toreset your password on Spotify, go toProfile>Account>Change Password.