Had the same issue. The problem is you have to release the email use from previous noticfication settings. Here is what you do. Click the "Cog" at the top right of the a screen to get to your profile. Once there click the Notifications tab You will now see your email address with an arrow next to it. Click the arrow and it will open a list of the emails you have on file. Uncheck the one you no longer want to use. Then you should be able to go back and make the new email address primary.
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