When I create a new task with a past due date, it will override by Today's date.
I can't see any validation rule about it.
I can chage it after create but is it possible to let the user set a past due date when create a new task?

Normally, there have a "New" button under the Fields & Relationships in an object. However, I cannot find this New" button under "Task" object.
How can I create a new field for it?

When I create a new task with a past due date, it will override by Today's date.
I can't see any validation rule about it.
I can chage it after create but is it possible to let the user set a past due date when create a new task?

Normally, there have a "New" button under the Fields & Relationships in an object. However, I cannot find this New" button under "Task" object.
How can I create a new field for it?