Ubuntu – How to scale title bars and menu in Ubuntu 14.04 or 16.04 with the terminal only

To keep the story short: Out of curiosity I wanted to know how the scale option would look like with value 5.something. Now I'm stuck with a highly oversized system where I can't change anything (because the window, which seems to be fixed in size) is too large so that I could change the scale value.
I get to the window where I can change the screen options, but that window is too large so that I can see the or reach the scale function or even save it.

I have already tried to reset the value using ubuntu on my laptop and counting how many times I have to press the Tab-button and where to change things etc. Since the terminal works, I need a way to reset the scale value to 1 using the terminal. Any other idea that works is fine for me as well.

I'm using the 14.04.1 version.