Thank you very much for your answer.
I located the xml file, but was not smart enough to figure out where to enter the font change for the note window.
In searching for "font" I come up with this. This is correct font for the text editor.
<text-editor-font-name>
<value>Saysettha MX 14</value>
</text-editor-font-name>
Regarding setting the default font, it would be very inconvenient to have a Lao font as my default font on my computer. Most of my work on the computer is in English and the Lao font does not have nice English characters. I really do hope there is a solution as I would like to be able to use the Notes and Reference windows in my project. (and even be able to see the Lao clearly in the search and replace fields).