YouTube keeps dubbing videos into another language

Annoying, yeah. On the video, tap the gear (or the three dots on mobile) > Audio track > pick the one marked Original. That's the quick fix. As far as I know there isn't a single account-wide off switch for viewers yet. The dub is picked based on your language settings though, so if you're fine with English menus, changing your YouTube/Google account language to English stops most of it. The creator can also turn auto dubbing off for their channel, but that's on their side.