Choose Options from the Tools menu. Word displays the Options dialog box. Make sure the Spelling & Grammar tab is displayed.
Figure 1. The Spelling & Grammar tab of the Options dialog box. Click on the Settings button. Word displays the Grammar Settings dialog box.
Figure 2. The Grammar Settings dialog box. Use the Spaces Required Between Sentences drop-down list to indicate how many spaces you prefer between your sentences.
Click on OK to close the Grammar Settings dialog box.
Click on OK to close the Options dialog box.