There is a simple solution that requires fewer steps:
in Office 365:
1. Go to Design Tab
2. Click the Watermark button (Earlier versions this is on the "Page Layout" Tab in the Page Background group)
3. Select Custom Watermark (at the bottom of the shortcut menu).
4. Select the Text watermark option.
5. Change the Text field to DRAFT.
6. Click OK.
The watermark now appears on all pages.