You have great control over object shadows. You can change their color, length, and direction. If you’re not familiar with the Shadow controls, create any drawing object and click Shadow Style > Shadow Settings on the Drawing toolbar. The Shadow Settings toolbar opens. Have fun playing around with the settings!
However, no such toolbar exists for text. You can simply turn shadows on or off. The workaround, from a Microsoft Knowledge Base article, is as follows:
Create an AutoShape, such as a rectangle and immediately (while the shape is selected) type some text.
With the shape still selected, right-click and choose Format AutoShape (or choose Format > AutoShape from the menu).
In the Format AutoShape dialog box, on the Color and Lines tab, in the Fill section, choose No Fill in the Color drop-down list.
In the Line section, choose No Line in the Color drop-down list.
Click OK. The AutoShape is now invisible; only your text appears.
With the AutoShape selected, click Shadow Style > Shadow Settings on the Drawing toolbar and modify the settings as you wish in the Shadow Settings toolbar.
Deselect the AutoShape to see the results.
Here’s an example. And no, I’m not suggesting that you use this effect for all your text.