Because the minimal system requirements have changed after you updated your iPhone SE to the newest version, the app may require an update. Apps must be supported by the current platform or iOS version of the phone in order to function correctly. If you haven't configured the app to auto-install updates, you'll have to manually install any outstanding updates. On your iPhone SE, follow these steps to check for and install pending app updates:

1. From the Home screen, tap the App Store icon.
2. Tap the Updates symbol in the lower right corner of the App Store main screen. The screen then displays a list of applications that have outstanding updates.
3. From the list, choose the Pandora music app, then hit the Update icon next to it. The Pandora app's pending update will then be installed.
4. If you notice many app updates, you may update all of them at the same time. To do so, go to the upper right corner of the screen and press the Update All button.