When you select Text Box from the "Items" box, you will be able to change the font, size and color of the text appearing in the drop-down list.
To modify any of the font attributes, select from the drop-down menus underneath each attribute. To bold, italicize or underline the text, click the respective icon.
To change the color of the background or font, select a color from the drop-down menu. If a color you wish does not appear, go to the bottom of the list and select "Custom...". This opens the color palette where you can create a color.
To change the size of a text box enter the desired height and width (in pixels) in the respective boxes.