Thank you for using Apple Support Communities. It's my understanding that you're receiving an error message when trying to update your Apple ID settings. I'm happy to help.
If you haven't already, try restarting your iPhone. Restarting can resolve many unexpected behaviors
Restart your iPhone, iPad, or iPod touch
If the issue persists, follow the steps in the link below:
Get help with iCloud
If behavior continues, let us know if this also occurs while connected with a Wi-Fi network. Include any other troubleshooting steps you may have tried.
Have a fantastic day!