Q: My Apple ID isn't accociate with I tune store

What have you tried so far on the device / computer that you are using to see if it fixes it ? Have you tried everything on here : If you can’t connect to the iTunes Store - Apple Support ?

The App Store cannot authenticate my ID and/or password, these credentials I've verified with my apple settings and are correct but the App Store does not accept them, what could the problem be?

What does 'cannot authenticate' mean, what exactly happens and where/when (are you trying to log into the account, to already logged in and just entering its password) ?