Deselect the “Edit all tasks” option for the desired user role
Click on “Save” Restricting task editing allows you to prevent certain groups of users from editing tasks including deleting tasks, adding or deleting subtasks, changing due dates, and assigning to other users. Users will still be able to see their assigned tasks and mark them as completed and edit the tasks they created.
In this example, Basic users are unable to edit tasks created by other users.