I'm trying to implement a simple approval process in SharePoint Designer. Everything is running smoothly except for one thing. People who weren't assigned to the tasks are able to approve/reject the task. I've looked at the PermissionSet and its value is AssignedTo. Same with TaskProcessOwner where I assigned it to the Manager.
Is there a setting that I am missing to disable the initiator of the work flow to be able to approve/reject a task?