Welcome to the Magix user to user forums, so not a contact for Magix Support.
Hence, I have extensively edited your post to remove ALL the supplied email addresses and serial number, with apologies! These are public forums and such confidential data should never be posted to them.
However, in order to amend your Magix account you need to go to this page, log in and go to User Details, and make the necessary amendments there. Clearly, since it appears you have more than one email registered with Magix you may need to amend them all.