Hello Mau6420,
If the Compass app as well as the parallax effect aren't functioning, I would start troubleshooting by quitting the Settings app and the Compass app as well:
Force an app to close in iOS - Apple Support
- Press the Home button two times quickly. You'll see small previews of your recently used apps.
- Swipe left to find the app you want to close.
- Swipe up on the app's preview to close it.
Then reset the phone and try it again:
Restart or reset your iPhone, iPad, or iPod touch
To reset, press and hold both the Sleep/Wake and Home buttons for at least 10 seconds, until you see the Apple logo.
If that does not solve the problem, I would next backup the phone to iTunes then restore the iOS from there.
How to erase your iOS device and then set it up as a new device or restore it from backups
Set it up without restoring a backup and test these functions again in a fresh install. If it works there then restore your backup and either verify that it still works, or if it stops that says there is something to do with the backup file itself.
If it does not work when you restore it, then it will need service:
iPhone Repair and Service
Thank you for using Apple Support Communities.
All the best,
Sterling