There are a few different places that the email address needs to be changed on your account. The first place you would want to start, is going to be in your "My Account" section (very top right of your Constant Contact page, that looks like the profile of a persons head).
In the "My Account" section, you want to be sure that the Username, Password, Security Question, Personal Information, and User Email section are all set to what you would like.
Once all of those changes have been made, we will then go to the "My Settings" page by clicking the icon that looks like a profile of a persons head. Under "Signature Information", you will need to edit that email address, as well as in the "Survey Response Notification" section. A place where you can verify new email addresses or delete old ones will be towards the top of your "My Settings" section called "Verify Address".