To amend the next Invoice number or set a prefix,

  1. Go to your Profile Icon (bottom left) > Settings

  2. Select Invoices from the menu.

  3. Click the Settings tab.

  4. Edit the Invoice Prefix value in the text box.

  5. Edit the Next Invoice Number value in the text box.

  6. Click Save

This allows for the next invoice number and prefix to be customised if needed.