Hi, this has been discussed already here:
https://www.wowinterface.com/forums/...ad.php?t=57394
TLDR: You have to use the upload API to mark an upload as "classic". There is no way of doing this via the web page upload interface. Also be aware that you can only have one single changelog per project. So if you want to maintain separate changelogs for retail and classic, it is better to have two separate projects.