When you decide to encrypt a file you should take care to delete or encrypt any previous unencrypted backups. It is also important to realize that when you change the password of your current data file, your backups still are accessible through the old password.
If TreePad SAFE or TreePad BIZ detect that a file is password-protected when commencing a numbered backup (Main menu ⁄ File ⁄ Backup to), they will ask you each time you backup whether you wish to encrypt it. This gives you the opportunity to save the occasional copy unencrypted if you wish.
If you select one or both of the Safety copy options (Main menu ⁄ View ⁄ Options ⁄ Backup), the hjt.bak file will automatically be encrypted.