If you’re using the ADSBx Pi image, the full UUID is stored in /boot/adsbx-uuid , but if you didn’t keep a copy of that from the old installation, you will have to start over with a new one (which is sounds like you have done … a few times!)
Just link the current feed UID (the one showing on the myip page) to your account, and unlink your old one. The others will disappear after a while (possibly 30 days).