You don't have an overall theme on your channel, it's good to keep a theme because it makes your channel look great and professional.
You also don't have a video category, you just seem to make videos on everything, this makes it difficult to gain subscribers because you can't find your target audience. This deducts a reason for the viewer to subscribe, you should choose types of videos that you want to create and stick to them. It's also easier to attract viewers that way because you know who you're trying to attract to your channel.
You should add custom thumbnails that are relevant to the content, make sure that the thumbnail is actual footage of what's in the video or gives some sort of information such as the title of the video or what the video does. A lot of the thumbnails don't match the title and get a bit confusing on what the video actually is.