Samsung SPH-I500SS-XAR - Manual (Page 129)

Section 2: Understanding Your Phone
2M: Memo Pad 126
Making a Memo Private
You can designate a memo to be “Private”. When the security features
are enabled, the memo is hidden or masked and not displayed on the list
of memos. To display the memo, a password is required.
Making a Memo Private
1. Tap the desired memo on the memo screen.
2. Tap the Details button to open the Memo Details dialog box.
3. Tap the Private check box.
4. Tap OK to exit.