The device policy that you choose will be applied to all of the devices for the users that you selected. If you activated ...

The device policy that you choose will be applied to all of the devices for the users that you selected. If you activated devices for users in the past, their devices will not be changed. To change policies on devices that you activated in the past, remove the users and add them again. If you want to apply custom policies on the devices, contact Microsoft Support.