To change line spacing to single or double space, use the Line Spacing button on the Home tab:
Select the paragraphs you want to change, or press Ctrl+A to select everything.
On the Home tab, click the Line Spacing button:
Choose 1 for single spacing, or 2 for double spacing.
Tip: If you want to change the spacing before or after the selected paragraphs, click Line Spacing Options at the bottom of the menu, and then click the arrows in the Before or After boxes.