Modifying User and Group Cluster Roles
To modifying cluster roles:
In the Clusters section, under the cluster name, click Roles to display the current user and group role assignments for that cluster.
The Roles can be displayed in list view or block view. Use the icons to switch between the views.
Block View displays the list of Cluster Roles and shows the assignment of users and groups to each role. You can add or modify the user and group assignment from this view. 
List View displays the list of users and groups with cluster role assignments. You can modify the user and group assignment from this view. Using the Block View, you can edit the user and group assignment to each role for the cluster by clicking in the space, typing the first character in an existing user/group name and selecting the name.
Using the List View, you can edit user and group assignments by finding the user or group, and adjusting the role using the dropdown.
Click the check mark to save the current, displayed assignment.