Select text that is styled with the style attributes that you want to change.
For example, to change the attributes of the Heading 1 style, select text that has the Heading 1 style applied.
Format the selected text with the new attributes that you want.
For example, you might decide that you want to change the point size for the Heading 1 style from 16 points to 14 points.
On the Home tab, in the Styles group, right-click the style that you want to change.
Click Update to Match Selection.
All text with the style that you changed will automatically change to match the new style that you defined.