To Edit Plot Label Styles

Edit plot label styles in the Label Styles collection in Toolspace, on the Settings tab or by selecting the Edit Label Style option in the drawing.

1. In Toolspace, on the Settings tab, expand PlotLabel Styles.
2. Expand a label type: Area, Line, or Curve.
3. Right-click the label style and click Edit.
4. In the Label Style Composer dialog box, modify style settings.

OR

1. Select the segment label to edit.
2. Right-click and select Edit Label Style.
3. In the Select Style dialog box, specify a label style, create a new style, or copy or edit an existing style.