Why can't I change to a different screen lock type?

If you have set up a Microsoft® Exchange ActiveSync® (EAS) account on your Xperia™ device, the EAS security settings may limit the lock screen type to only a PIN or password. This occurs when your network administrator specifies a specific lock screen type for all EAS accounts for enterprise security reasons.

Contact the network administrator of your company or organisation to check what network security policies are implemented for mobile devices.