Modify a style
On the Format menu, click Style.
In the Styles box, select the style you want to modify, and then click Modify.
Click Format, and then click the attribute ? such as Font or Numbering ? you want to change.
Click OK after you've changed each attribute, and then repeat for any additional attributes you want to change.
Tip To use the modified style in new documents based on the same template, select the Add to template check box. Word adds the modified style to the template that is attached to the active document.