Unity 5.0.2 UI Text - Best Fit isn't working correctly?

So I'm making a menu in Unity that is supposed to support multiple resolutions. My buttons scale, but the text inside them does not.

I've experimented with anchor points, but I've been told that the "Best Fit" option is the best way to go for text scaling. However, while the text does become bigger, it doesn't scale dynamically according to screen size, which is what I want. So if the screen becomes smaller, the text should get smaller with it, which isn't happening.

Anyone know why this is happening? Is Best Fit not what I should be using?