For Highlighting and the Note's icon, I can click on it, and choose to view the Property bar and change its color, icon image, etc, and then say, "Use as Default Property", so now all the highlighting and Note icon will have that style.
I can even change the default font size by going to Perferences -> Commenting, and use Verdana 18px.
But I can't make the Note Icon bigger, so that it is really obvious, possibly about twice as wide and twice as tall... weird. Is there actually a way?