I said everyone who "owns" the game, note the quotation marks. I've mentioned a few times here in the posts that I also did not know how this works here on itch and recommended to buy the game for the cheapest price possible as long as it was possible if you wanted to make a 100% sure.
There's one thing you can try though, but I'm not sure if this works for anyone other than me, so be aware that you might delete the game for nothing:
If the game is in your library > delete the game, from your library > re-download the game (if it lets you).
Since the old version is not available anymore, it should only be able to download the new version.