Selecting your UI
Since the touch-enabled UI supersedes the classic UI, the user or administrator of the AEM instance must make an active decision to continue using the classic UI. Because the classic UI is no longer maintained, there is no way for the authoring user to simply switch from the classic UI to the equivalent in the touch-enabled UI.
For convenience to authoring users, the touch-enabled UI does allow for switching to the classic UI when necessary. See the Selecting your UI in the standard Authoring documentation for details.
Instances upgraded from a previous version will retain the classic UI for page authoring.
Configuring the Default UI for Your Instance
A system administrator can configure the UI that is seen at startup and login by using Root Mapping .
This can be overridden by user defaults or session settings.