I believe you have a similar problem that I have had with my channel. The problem with "how to" and other tutorials is that people often find you channel since they have a problem. When the problem is solved they don't need your channel any more. Let's say I have a problem with my USB device, I search for the problem, I find your "Unresponsive USB Device FIX" video, it helps me and fixes my problem. I may click the like button, but why would I sub? My problem is solved and I have no reason to visit your channel again.
Lets say I'm a bit more curious, I'm not just trying to solve a problem, I want to learn stuff. I'm interested in crypto currency and find your "get started using cryptocurrence using coinbase" video. I like the video and decides to check out your channel. But when I check it out I don't find any more videos about crypto currency, instead I find videos about Pumkin Pies, iPhones and work outs, stuff that have nothing to do with why I found your channel or the topic I'm interested in. Why would I sub?
To my experience smaller channels who focus on how to and tutorials often get more views but less subs compared to other similar sized channels. One way to get more subs would probably be to niche yourself more, just making how to videos focusing on a few topics, so when I find your crypto currency video and then check out your channel I find a lot of other crypto currency videos or if I find the iPhone video and check out your channel I find more iPhone videos. Now you are offering more content that I'm interested in and the chance of me subbing will be greater.