I saw in another post that I was supposed to edit: wp-includes/widgets.php and where it uses the Template Tag, wp_tag_cloud(), add the smallest, largest, and unit parameters to meet your needs.
and in another
To change the font sizes, edit wp-includes/widgets.php using information found at:
basically, you want this:
But I can't even find where I am supposed to do these things. I looked in my Theme as well, but didn't see it there (though I was able to change the font size for the text in my general blog posts
[mod: moved to: 'How-To and Troubleshooting']