The invoice numbers in QuickBooks are typically assigned automatically based on the existing sequence. However, you can work around this limitation by following these steps:

Void or Delete Existing Invoices (Caution):

Voiding an invoice keeps a record of it but marks it as "voided," so it won't affect your financials.
Deleting an invoice removes it entirely, including from the records.
Adjust Invoice Numbers:

After voiding or deleting the invoices, you can create new ones with the desired invoice numbers. QuickBooks usually assigns the next available number in the sequence, but by voiding or deleting, you can "skip" numbers.
Customize Invoice Number Manually:

In your new invoices, you can manually input the desired invoice number. Keep in mind that this may require more effort on your part to ensure that you don't duplicate numbers or create confusion.
Set the Custom Invoice Number as Default:

You can set the custom invoice number as the default for future transactions. This can be done by going to the "Custom Form Styles" and editing the invoice template.
Contact QuickBooks Support:

If you are unable to achieve your desired result through the above steps, it's recommended to contact QuickBooks support for guidance. They may provide additional insights or potential workarounds.