yeah youtubers change titles and thumbnails to see if it'll get their videos more views. sometimes they'll even change it back to the original if they see no change. it also can help trick people into thinking it's a new video, because the title and thumbnail are new, and so people might click on it to watch, not realizing it's the same video they already watched(i'm referring to it showing up in the recommended page, or the recommended list when you're watching a video, as it won't show that you've already watched it like it does on your sub box)