Top bar widget icons

Is there a way to specify which icon to use for each top bar widget? They appear to be hard coded into the template-parts.php file. I tried moving a copy of this file into my child theme and customize it there, but the changes were not seen when reloading the page. The only way I was able to specify the icon was to edit the template-parts.php file in the main theme, which I do not want to do.