Or if you aim to change the icons themselves, they are scattered here and there some are found in /template others are found in /modules
The majority of the files are .svg format, which win 10 does not read. But this little piece of software will enable windows to preview svgs
https://github.com/maphew/svg-explorer-extension/releases
UNA is like a point and click adventure game. In most cases, to do something specific, you will have to go and solve puzzles in 5 different locations first. And to add to the excitement - there is no map!