How to change the email associate to certificates

Hello everyone, 

I have a question about the email which associate to the certificate. 

1) When I buy a password I use email A, when I attempt the assessment, I use another account with email B. Which email will associate the certificate?

2) In my case, emails A and B are the same. But when I change the email in my profile, the email associate with my certificate doesn't change. How can I change the email which associates with my certificates? just in case, I have an issue with my email.

Thanks,

Nhan Le