You can easily enable the Settled On Invoice number in the Credit Note PDF in Moon Invoice by following the steps below.

1. Open the Moon Invoice application on your device or tap on this link.
2. Navigate to Settings → PDF & Print Settings → now choose Credit Note from the top left corner.
3. Now go to Header → enable Settled On Invoice # option and save.
4. Once it’s enabled, the Settled On Invoice number will appear in the Credit Note PDF.