Why are the shields not upgraded?

I really don't understand the way shields are supposed to work.

I know that you need to upgrade them, and I have done so for every game that I've played. But why is there only ever one blue marker in the top left-hand of screen when I've upgraded to 60%?

When I hover over the shields button the tooltip says "Partially Powered, Manned by Crew", but I have 15 unused reactor bars and still the shields don't power up? I appreciate that the additional unpowered bars help protect the system, but I want my goddamn blue shields please. I'm getting nailed at the later sectors.

Why haven't my shields upgraded?

The problem you're having is that you aren't actually giving the shield any additional power.

In your screenshot, there are four unpowered nodes on your shields. Simply add power to those nodes by clicking on them (like you would to add power to any other part of your ship), and you will be able to fill those extra empty shield bars.

Each level of shield requires two power for the full effect, so you would need to add four more power to your shields.

It should look something like that.

You need to actually click on the shield icon on the bottom left to transfer power from "unused" to "shield".

A fully upgraded ship won't actually have enough power bars to power every component fully, forcing you to choose what you want to power. At the moment this isn't a problem for you. This is why it is not done automatically.