Editing ACH info for recurring contributions - iATS
You are correct - you can not Edit ACHEFT Card on File via the CiviCRM interface: (left: ACH/EFT; right is Credit Card):



To Edit the Routing + Account Number associated with the ACHEFT recurring series go to iATSpayments.com -> Virtual Terminal -> Customer Database -> Find the record -> hit Edit -> and make Edits to the Payment Information section. This will change the Account Number (or Credit Card) that is attached to the token that is already associated in CiviCRM with the recurring series; Remember to leave your Recurring Payment Settings to OFF here -> otherwise your donor/member will be processed twice -> once triggered from CiviCRM and once triggered from iATSPayments.com