Yes, well, people who have experienced this issue have all had Secure Notes that worked fine, until one day when they didn't.
Between 10.4x and at least 10.6x Secure Notes have had issues.
Basically, you open a secure note, add text to it, and when you open it on another occasion all previous text is gone, plus you latest entry, and the note is seemingly blank.
I do know how to use the Keychan.
The issue will also show if you import backed-up Keychains.
Maybe you are unaware, but this has been a persistent and frustrating issue for years (ever since the release of 10.4x). Most users who have experienced the issue moved to 1Password.
Personally I much prefer a secure file storage solution that is part of the OS so that I do not have to trust a third party to maintain software (or continually pay to upgrade said software with a new OS version install due to incompatibilities).
You can do a quick search of Discussions to see some background on the issue.
I will say this ... if the issue was not fixed with Mountain Lion, your Secure Notes (" which work fine") are at risk of becoming unusable and unrecoverable.
Thus my question.
You need to export the keychain from your last system to this one, and it will be there under Keychain Access. (you can just copy from a backup).
You can rename it to keep it unique from your current system Username if you used the same one on both systems, but it won't be necessary to be able to tell them apart since your current login keychain will be bold type (if you're set to automatically load that keychain on login).
Select the old keychain and enter the login and password from your last system to access the old notes. You could copy the contents to your current User Login keychan or just keep using them under the old one.
Even though your login and password might be the same for the new and old systems, the permissions differ. That's the root of your issue.
You should periodically backup you keychan so you will always be able to keep things like secure notes you've created for use on any other system.
Can you look at my other post on this here just to see where I am at rather than me explain it again?
I don't know where you mean to enter the login either. My login gets me into the computer so where ese could I log in? Yes I did have the same username
After you import the old keychain file (your login keychain from the old system backup) it will appear in your list of Keychains (top left) once you launch Keychain Access. Click on the Keychain you want to access.
Below that list you might need to select "All Items" or "Secure Notes" under "Category". Your Secure Notes from that Keychain will show in the main window.
Double-Click on a Secure Note to view. When it comes up (in a new window) click on the Checkbox "Show Note" and you will be prompted for a password. Enter the password you used on the old system (or a different one if you elected to use a unique one for your created Secure Notes on the old system).
Alternately you can click on the padlock icon in the top left of the menu bar to unlock the Keychain after you select it as above.
It's always been my habit to create a new Keychain rather than use the login Keychain for my secure notes. That way only Secure Notes are in it. Makes for simpler backups; the System is going to create a new login Keychain with Certificates, etc anyway whenever you create a new User Account on any System, so you don't really need to back that stuff up.
Keeping my user-created content (like Secure Notes) separate from the System-created content (Certificates, etc) makes keeping track of my backups and data easier for me. So I create a new Keychan and use that instead for my Secure Notes.
perhaps you could have a look at my keychain related discussion thread, which revolves around the os refusing to allow me to eject my private keychain which is contained on a usb stick, untill ive quit early all open applications, bear in mind my private keychain contains only secure notes created by me the user, and yet in snow leopard it thinks some opens apps have dibs over it ?