Word files that contain personal details, bank account numbers and other kinds of sensitive information can be password-protected while saving. In Word 2003, open the Save dialogue box and tick Tools, followed by Security Options (in Word 2007, use Tools, then General Options). Type a password and then click OK. You'll be asked to confirm the password, after which the document cannot be opened without it. To remove protection from an existing document, re-save it after deleting the password.