To Modify a Style Definition
To modify a style definition:
1. On the Annotate tab, in the Format group, click 
Manage Text Styles. The Text Style Gallery dialog box opens.
Manage Text Styles. The Text Style Gallery dialog box opens.2. Select the style to modify and click Modify. The Modify Text Style dialog box opens.
3. Use the dialog box to make changes to the style definition. Click OK when finished.