My Apple ID is my old email and I want to change it but can't because my rescue email is my current one.
There are instructions on this page for how to change your rescue email address (you may need to log out and back into your account before trying to use it as your main address) :
Navigate to appleid.apple.com using your web browser.
Click "Manage your account"
When prompted, sign in using your Apple ID and password.
Click Password & Security
You'll be asked to answer 2 of your 3 security questions before you can make any modifications. If you are unable to remember your answers, you can choose to send an email to your rescue email to reset your security questions.
After you've validated your identity by correctly answering your security questions, click Edit to the right of your rescue email address.
Once you've finished editing your rescue email address, click the Save button directly below the email field.