Is it possible to change some of the parameters, without the customer having to approve these changes of parameters?

Available parameters for update are: 

  • amount
  • plan
  • description
  • next_payment_date
  • frequency.
  • external_id
  • success-callback
  • cancel-callback

Customer needs to approve agreement on creation and that's it. After that merchant can send an update agreement operation and update/change some properties, but not all.  Customer doesn't need to approve agreement updates.