I've already replied to your email on this, but just in case someone with a similar issue happens across this thread, here was my reply:
Any auto-return URLs you configure in PayPal would only work for PayPal's own purchase buttons. Our system has no way of picking up any of your PayPal account configurations from PayPal's end, so for every order sent to checkout, our system provides thank-you page return URLs defined at our end. This help page explains our Redirection features in more detail:
If you want to use Redirection to show product-specific thank-you pages, make sure that:
- You do not have a Common Thank-you Page URL defined in Seller Admin > Account Preferences;
- You have not customized your E-junkie-generated thank-you pages (nothing in Seller Admin > Account Preferences > Common Thank-you Page HTML and nothing in the "Message (HTML)" field of specific products' settings).