Approval Task custom fields need to update in new list for every approval

I had customized nintex approval task form, added few custom fields. Those fields need to update in new list for every task approval.  The scneario is if group of people in assign flex task -  the tasks are created individually, every individaul task approved need to update the items in new list. I used in nintex workflow but it is update only after all of the task is approved.