Are you ready for brain surgery? We are referring to GnuCash's brain. As we saw earlier, GnuCash starts invoice numbering at 000001 and keeps incrementing it. What if you want to start the next invoice at 002501? Unfortunately GnuCash doesn't provide a User Interface for setting the starting invoice number. However, we are not the types to give up so easily. So, we are going to get it done by opening the GnuCash accounts file and directly editing the last invoice number stored there.