incorrect email in apple id

I have an incorrect email in my account. I have followed the advice from others on the forum but i cant seem to correct this.

Everything is showing in my account details ok until i attempt to install an app from the store. It is asking me to enter my password for the incorrect email address which is misspelled and does not exist. I cant get it to show my updated, correct address as per my updated account settings. I have cleared browsing history, reset password etc.

Thanks.