To Edit a Style, from Page 193 of MS Word Manual for V6:
To modify the formats of a style by using the Style command
From the Format menu, choose Style.
In the Styles box, select the style you want to modify.
If the style you want to modify is not listed in the Styles box, select another category of styles in the List box.
Choose the Modify button.
In the Modify Style dialog box, choose the Format button and modify the style's format.
If you want to use the modified style in new documents, select the Add To Template check box. Word adds the modified style to the template attached to the active document. The modified style will be available in all new documents you base on that template.

Choose the OK button to redefine the style.

Repeat steps 2 through 5 to modify additional styles. Then choose the Close button to close the Style dialog box.