Why is the green leaf in the energy settings missing and slider is at 50% again after restart?

I click the battery icon in the taskbar and put the slider to the left.
The icon in the task bar now shows a green leaf.

It looks like this:

I restart Windows, and the green leaf is gone.
I click the battery icon, and I see that the slider is in the middle and the text says “Balanced”.

How do I keep the slider where it was before a restart?