To assign a password to a single project file:

1. In the Project Explorer, find and right-click the desired file, and then click Password Protection on the shortcut menu. The Edit Protection dialog is displayed.
2. Type the new password, and then type it again to confirm.
3. Click OK to close the dialog.
4. The file is now protected. The next time you try to open it, you will be prompted for the password.
5. To clear the password, open file for editing, right-click the file in the Project Explorer and then click Password Protection on the shortcut menu. In Edit Protection dialog Leave the New password and Confirm password boxes empty.