Instructions provided are for changing the size of a label or text background symbol in ArcMap.
- Select your document's table of contents and double-click the desired layer.
- Select the Label tab.
- Click Symbol to open the Symbol Selector. Don't change size or color here, for it will affect only the text.
- Click Properties to open the Editor.
- Click the Advanced Text tab.
- Ensure Text Background is checked and click the Properties button to open the Editor for the Background.
- Change the properties to alter the appearance of the text background.
Selecting 'Scale Marker to fit text' will resize the marker based on the font size for your text.