How do I add an email to "notification email on submission"

I added a 2nd email to receive notification when a form is completed.

When I send a test it only goes to the email attached to the account 

I believe I addressed your question in this thread here:

https://www.jotform.com/answers/826099

The test email will always be sent to the default address associated with your account.  To test further emails, you would need to send a submission through the form.