font size too small in help screen

The font size in the help screen right panel is too small to view comfortably. I am using ubuntu 16.04. Adjusting the ubuntu defaults increased the font size for the left panel text (the index panel), but did not change the font size in the right panel text, which is still about a 8pt text. How do I adjust the text size in that panel?

The right part is actually like a browser. You can increase or decrease the font size by Strg+MouseWheel.