Creating & Saving Invoices with next number capability

Hi everyone,

I am quite new to Excel and I am having problems setting up an Invoice program on my MAC running Catalina 10.15 and I am using Excel 16.36.

I would like to create a personalised Invoice that when its been filled out can be saved to a folder on my computer and cleared of its contents with a follow on invoice number ready for the next sale.

I have created the Invoice I need and have managed to enable the clear contents command, but cannot save it and create next invoice.

Would be very grateful if anybody can help me.

Regards,

Rob