1. Go to Settings
  2. Click on Documents
  3. In the "Document Sequences" area, click on the document you wish to make changes for, you'll be prompted for next sequence number.
  4. Enter the next invoice / credit note number and click "save"
  5. Note: you can choose to enter a lower number in step 4. However, when generating the next invoice, the system will ensure that invoice numbers are always unique, so the system will skip forwards from the number you entered until the next available unique number.