I have iCloud set up on my iPhone 4s. But when I go into the settings menu, the icloud/Twitter options are grayed out and not working. I am unable to open them. Mail,Calender,and notes with the iCloud accounts have the same issues. I can log into icloud.com website and Appstore is logged in.
How to fix iCloud option issue
* Reset all settingon the phone. Go to settings > General > Reset, tap “Reset all settings” and set up as new device via icloud.
* The Parental restrictions turned on during the iOS update may cause that.
Tap Settings > General > Restrictions > Accounts allow changes.