I changed my password but my Apple ID is still disabled. How do I fix this

Did you follow all of the instructions on the page that you posted from i.e. also did : What to do after you change your Apple ID or password - Apple Support ?

If you did contact iTunes Support and see if they can/will re-enable it : http://www.apple.com/support/itunes/ww or https://www.apple.com/emea/support/itunes/contact.html

Since you have already done what was recommended in a previous post:

What to do after [or before] you change your Apple ID email address or password - https://support.apple.com/HT204071 - "After you change your Apple ID email address or password, you might need to update your sign-in information with any Apple services you're using." - Or if you're seeing persistent disabled messages or repeated requests for the password to your previous Apple ID.

If you cannot resolve it yourself:

Contact Apple for help with Apple ID account security - https://support.apple.com/HT204169

Follow the instructions from this support article > If your Apple ID is locked (disabled) - Apple Support