To manage all tasks for a clinic (even if they are not assigned to you or roles you have) you can see those tasks under "Task Management" on the Practice Manager dashboard.
Here you can choose "All Open Tasks" which will show you all of the uncompleted tasks for your clinic. On each row you can see the "reassign" icon which will open the reassignment editor:
Just as with the individual task, you can reassign the task to an individual or a role. In the reassignment editor you can also change the icon associated with a task as well as the tasks priority. These can be modified without actually reassigning the task.