There are actually two different email addresses in the system. One is your "user" email associated with your user account. You can change this through your profile page where you change your password.
The other email is displayed on your Blog Options page, is an email address where blog related emails will go (like emails about new comments or blocked spam). This email needs to be confirmed before you can change it. There's a note under that box that says:
"This address is used only for admin purposes. If you change this we will send you an email at your new address to confirm it. The new address will not become active until confirmed."
If you change that email, you should get an email sent to the old email asking to confirm the change.
If this doesn't work for you. Please send us mail at support@sweat365.com with the email you'd like to change it to and we'll get you set up.
As for your other blog. Can you send us details about the Blog address you're trying to use? We can help you get that working too.
Thanks!