You can password-protect a OneNote 2013 section if you want to control who can read its pages. Before you password-protect a section, consider these password restrictions:
To search password-protected sections, you must open them first and conduct your search within ten minutes of opening (you can change this setting on the Advanced tab in the OneNote Options dialog box).
You can’t share password-protected sections with OneNote Web App or OneNote mobile apps.
Passwords are case-sensitive (you must enter, and remember, the right combination of uppercase and lowercase letters).
Right-click the section tab of the section to which you want apply a password.
On the shortcut menu that ...