User groups are assigned to a queue in the User Groups tab of the Properties pane.
To assign a user group to a queue:
If you want to assign all of the user groups currently assigned to the life cycle to the selected queue, click Add All Assigned to Life Cycle. After clicking this button, if user groups are added at the life cycle level, the queues user group rights are not automatically updated.
Note:
When you remove a user group assignment to a queue, if ownership is being used and users belonging to the user group that was removed no longer have access to the queue via another user group assignment, the owned items owned by these users will be labeled as unowned.