I experienced this security feature in Microsoft Dynamics AX2012 and would like to share it with you all. 
Follow the steps below:

1.1 Go to System administration > Common > Users > Users
1.2  Select the required user from the user's list.
1.3  From the upper-left corner of the user list page, Click on "Edit" Button.
1.4  In the center of the user form, Click "Assign Roles"

1.1  Select role name to assign to the selected user.
            1.2  Click "OK" button 
            1.3 Click "Close" button on the User form

We selected the user first, and then assigned a role from the predefined roles list
by marking the role from the left box appeared for every record.