Users can manually create their number series by typing the sales receipt number in the sales receipt #. 

1. Click on Sales Receipt 
2. Click on the '+' sign to generate a new sales receipt
3. Manually add sales receipt number in invoice #, e.g., Moon SR 1
4. Enter other details and click on 'Save.'

After creating a sales receipt series, all the upcoming sales receipts will be saved in the succeeding number—for example, Moon SR 2, Moon SR 3, and so on.