Text Boxes are frequently used in Word to draw attention to important information. They float above the Document Layer and reside in the Drawing Layer. Therefore, you’ll want to avoid the use of Text Boxes and instead use and modify the Intense Quote style to make text stand out if it is important, or create a custom style for this. The following movie tutorial will show you how to create a custom style for callout text.
Remember that screen readers will not present visual information, such as bolding, borders, background colors and highlighting. Sometimes, screen readers can be set to describe visual information, but it is not typically done. The information can be overwhelmnig and irrelevant to screen reader users. To designate important information, you can start the sentence with “Attention,” or “Note.” “Warning,” and “Important” are also usable choices to draw the attention of a screen reader user, as well as sighted users.