Microsoft has modified some of its processes for managing User Account Control (UAC) in Windows Server 2012. By default, UAC will now be enabled in Windows Server 2012.
Change UAC setting from control panel
Click Settings on the right of the desktop to open the Control Panel.
Click on User Accounts to change User Account Settings.
Go to Server Manager and select Local Security Policy in the Tools
right-click User Account Controls: Run all administrators in Admin Approve Mode