Excel invoice template numbering

Ive tried to help a friend make an invoice-that he could keep reusing each week to bill a client-using Excel’s invoice template on his home pc but I cant figure out how to make the invoice numbers change automatically,(They are supposed to change sequentially but they don’t) AND every time he prints one, he has to change the print properties to color from black & white but I dont think that it is a result of the printer’s settings, I think it should get the default settings from excel? I’ve wasted hours on these 2 stupid problems & I’m going MAD
HELP