This is happening because
Notezilla syncs on startup and gets back the latest sticky note back from the cloud.
After you restore from the backup, immediately right click on the
Notezilla icon choose Sync from the menu and disable "Sync automatically" option so that syncing is not triggered.
Then go to the restored sticky note, modify it a bit so that it is not replaced by the cloud version of the sticky note.
You can then enabled "Sync automatically" option.