On the Page Layout tab, in the Page Setup group, click Margins.
Click the margin type that you want. For the most common margin width, click Normal.
When you click the margin type that you want, your entire document automatically changes to the margin type that you have selected.
You can also specify your own margin settings. Click Margins, click Custom Margins, and then in the Top, Bottom, Left, and Right boxes, enter new values for the margins.
To change the default margins, click Margins after you select a new margin, and then click Custom Margins. In the Page Setup dialog box, click the Default button, and then click Yes. The new default settings are saved in the template on which the document is based. Each new document based on that template automatically uses the new margin settings.
To change the margins for part of a document, select the text, and then set the margins that you want by entering the new margins in the Page Setup dialog box. In the Apply to box, click Selected text. Microsoft Word automatically inserts section breaks before and after the text that has the new margin settings. If your document is already divided into sections, you can click in a section or select multiple sections and then change the margins.
