Require a password to open a document When you create a password, write it down and keep it in a secure place. If you lose the password, you cannot open or gain access to the password-protected document. Learn about using passwords. Open the document. On the File menu, click Save As. On the Tools menu in the Save As dialog box, click General Options. In the Password to open box, type a password, and then click OK. In the Reenter password to open box, type the password again, and then click OK. Click Save.