Firefox user help can't change this you need to go to your firefox account and make and then verify the email notification of the change.

https://support.mozilla.org/en-US/kb/change-your-firefox-accounts-password

I have a new email address. Need your help

Are you referring to your primary email in your Firefox Account?

https://support.mozilla.org/en-US/kb/change-primary-email-address-firefox-accounts

btw ignore the suggestion by Dropa above to reset your Firefox Account password as it will delete everything you have synced.

Note that you still need access to the old email address to be able to confirm a secondary email address if you haven't done this yet.

You can add a secondary email address and confirm this address. Once it has been confirmed, you can make the secondary email address your primary email address.

• https://support.mozilla.org/en-US/kb/change-primary-email-address-firefox-accounts
• https://support.mozilla.org/en-US/kb/add-secondary-email-address-firefox-accounts
• https://support.mozilla.org/en-US/kb/ive-lost-my-firefox-sync-account-information