Go to https://appleid.apple.com/ and click 'Manage your Apple ID' on the right-hand side of that page and log into your account. And then on your account's page click the Edit button to the right of your current email address
I've just come back to your reply because I've just discovered why I do not get notifications: Apple still has my old defunct email address !
I've tried to change it, but tells me that the old address cannot be changed !!
So I tried to set it up as an alternative address.
Then it told me that it is verified for another Apple ID !! That is not possible - unless somehow it happened when I tried to set up an iTunes account, but gave up when it got too complicated.
But more to the point, I DO NOT want an iTunes account !! So where do I go from apart from leaving the Apple communities for good