Select the text or text box you want to edit.
Open the Format menu and choose Line Spacing.
The Line Spacing dialog box opens. Click the up or down arrow to change the amount of spacing between lines of text, and then click OK.
PowerPoint adjusts the line spacing.
Line spacing refers to the amount of space between lines of text in a paragraph. You can control line spacing in PowerPoint using the Line Spacing dialog box.
Other Line-Spacing Options
The Line Spacing dialog box also offers controls for setting the amount of spacing before and after paragraphs. Generally, however, if you use too many paragraphs on a slide, it's more difficult for the audience to read the material.