If you have recently changed Apple IDs, you can copy your notes on iCloud from your old Apple ID to your new Apple ID using the following steps:
1. Log into your device with your old Apple ID
2. Open Notability, and if iCloud sync was not enabled in Notability's settings, please switch this on and wait for your notes to sync to your device.
3. Once your notes have loaded in your library, switch iCloud sync off in Notability's settings, and when prompted select keep on my iPad/MacBook/iPhone.
4. Close Notability and log out of your old Apple ID in your device's settings
5. Log in to your new Apple ID
6. Open Notability. (Since you chose to keep your notes on your device, they should all still be here)
7. Switch on iCloud sync in Notability's settings. This should now sync all of the existing notes in your library with your new Apple ID.