It's all very weird but it does make sense, the problem I was having was I was just expecting the resolutions to 'work' and fix themselves when I exported my project to my phone. Well that's not how it works, you've got to fit the design of your game entirely around the resolution of the phone in order for it to correctly scale everything otherwise it will cause all kind of weirdness with the buttons and sprites.
You see the white border line in the screenshot I've provided? It turns out that Unity has a whole bunch of preset resolutions specifically for this sort of thing. You need to put your game in either portrait or landscape or figure out a way to have the game in either mode, this explains why most games only have a fixed resolution because otherwise they would have to fiddle around with the positioning of all the images on the screen constantly and it just wouldn't work.
Now thanks to working all of this out I can focus on the actual games development and I've just run into an annoying problem with the way the buttons are working but at least I'm back to real programming now. I'm going to have a think about the theme of my little top down shooter as well and I may even switch it to landscape because I personally feel this would be a better option for this type of game.