How to update Who_id or Parent_Id on a Note, Activities, Etc.

How to update Who_id or Parent_Id on a Note, Activities, Etc.

Looking in the API I can't find a good example of updating the Who_id or Paernt_Id on a Note, Task, Event, etc. to re-assign it to another contact.

I'm doing this:
  1. PUT https://www.zohoapis.com/crm/v2/Tasks/1234567890
  2. {
  3.  "Who_id": "IdOfContactHere"
  4. }

This doesn't seem to work, even though returns 200 with a SUCCESS code but doesn't show up in the contact specified here: "IdOfContactHere"

How does one do this correctly?