Notezilla will always replace an older note with a newer note. It may be possible that the Notezilla sticky note was accidentally modified on the Windows desktop. Only then the note on the iPhone could have been replaced too.
Also ensure that the system times on your iPhone and your PC are both the same.
To ensure that the desktop is synced up to date:
- In your iPhone, edit the existing sticky note, go to "Sync" and tap on "Sync Now" button
- Go to the desktop back, right click on Notezilla icon, choose Sync option and click on Sync Now button
You will now see the updated Sticky note with all the modifications, on the desktop.
Sync on Notezilla happens every minute.