I know what you're talking about. And you know what I'm talking about as well: read and do a search for FIFA 17/18 threads that discuss how to export/import stadium files, and how to add/switch stadiums. You say you looked in the Editor and can't find the stadium files. Well it makes sense that any FIFA 17/18 stadium thread will tell you where the stadium files are located, or at the very least which files you need to export/import. Start with that. Check the Moddingway site and Google as well, do a search for info on stadium files for FIFA 17/18.