Editing Tasks
You can edit tasks depending on their status and your security rights. For example, you can edit a task description, attributes, change an owner of a task, or end date.
For an Open task in a Task List, you cannot edit the start date, because the task has started. You can only change the duration or the end date. You also cannot edit instructions, questions, and you cannot add, delete, or edit predecessors. You can reassign the Assignee or approver from the Task Actions workflow.
To edit a task: