I am trying to double underline a range of cells so that the underline fills the width of the cell. I followed Excel Help instructions as follows:

You can apply a different style of underline, such as a double underline or a single or double accounting underline (an underline that fills the width of a cell). On the Format menu, click Cells. On the Font tab, select the style that you want in the Underline box.

However, when I followed the above instructions, it did not fill the "width" of the cell. What am I doing wrong?