Moving this discussion to the Adobe Digital Editions forum.
Charlies756 if you have changed your Adobe ID then you will want to contact the providers of your purchased content to reset the activation on the titles you have purchased. Once you download and activate under the new Adobe ID then your purchase content will then be tied to your new account.
You want to make sure you keep the same AdobeID but associate it with a different email address.
If you get a new ID, your won't be able to read the books purchaced on the old one.
To change the email associated with the ID.
Books are associated with the ID (remembered by an obsure code called a guid),
and the email address is also associated with the ID.
The book is not directly associated with the email address.
Some devices may still show your old email address as your AdobeID; but it should all work ok anyway.