Hi, Pat.
I believe this a function of the Font itself (someone can/will correct me if I am way off course).
If you use fonts like Bookman Antiqua or Century Gothic or Garamond and such, you will find that underlines are narrow when the word is bolded also.
You could give the underline a color and have appearence of being narrow.
Other than that, Arial, TNR and such are going to give you bold underlines.
Member- AAAA Association Against Acronym Abusers