WHM notices about changes to a cPanel
Just go to WHM, List Accounts. You can update the contact email for each account there. Changes to an Account will notify the email listed. New account creations only go to the reseller owner (see WHM notices).
You can only send WHM notices for a cPanel to one email. This should be the reseller owner's email, as each cPanel user can set their own contact email in cPanel for cPanel notices.
cPanel notices
Each cPanel user can setup their own notices for events which happen in their cPanel. They go to cPanel and click the Update Contact Info icon, under Preferences.
WHM notices
How do I update the email contact for WHM notices about WHM?
Simply go to List Accounts and update the email contact for your primary domain name (the one associated with your billing account).
Is there a way to change the email address from where the email is sent?
No, this email will always be sent from the server (whm_user@server.domain.com).