Help with printing from POS Thermal Bill Printer

I recently purchased a Model # SC9-5870 USB Thermal Bill Printer, from ebay, and when I try to print a receipt from my Merchants Webpage, the font size is really small, I tried looking into the software driver printing settings, I could not find anything on increasing the font, I tried searching Google for a company but this printer is not branded! Is there another way to increase the font size maybe windows 7? I called my merchant company and of course they don't support my $60 printer but they will support there $200 printer they sale! Can anyone help me! Anything would be greatly appreciated!