What Is a Podcast App?

If my episodes get uploaded through a different software platform, often the subtitles won't work. If I directly upload an episode to YouTube, without going through another website or pit of software, if I go directly onto YouTube, the subtitles almost always work. For some reason, sometimes YouTube just goes, uh, no, sorry, not possible. No subtitles. That's what happens with YouTube sometimes, and I don't really know why.