Cannot Sign In in the xbox app (beta) after I change the email of my Microsoft account

Have you checked in your email that you set to your new email, to see if there is anything from Xbox to activate the new email? Sometimes you might get a verification email and you need to follow a link within it to activate it. If that email hasn't been
activated yet, it might not recongize the new email login until you do.

• 
  On your PC, go to
  Xbox.com and select Sign in. If there are problems with your account, the instructions will help you solve them. If you can’t go beyond the sign-in screen, select
  Forgot my password and follow the instructions.
  
• If that didn’t work, select the Start
  button > Settings >
  Time & language. Under Date & time make sure the
  Set time automatically setting is turned on. Open Time & language settings
  
• If none of those options work, select the Start
  button > Settings >
  Accounts , then find the Microsoft account you used to sign in to the Xbox app and select
  Remove. Then go back to the Xbox
  app and sign in with the Microsoft account you just removed. Open Settings
  

You can change the email address associate with the account but you cannot move it to a different MS account. http://support.xbox.com/en-US/my-account/microsoft-account/change-email-sign-in-for-microsoft-accoun...

I have managed to resolve the issue I believe. The Microsoft store was signed in with my non xbox email. I have signed out and then in with my xbox account and appears to have resolved the issue on the Xbox Beta App. Many Thanks.

You can change and update the email address. If an email has been used on an account you cannot transfer to it.

change email address