give this a try,
Set up a workbook as you want it (margins, number of sheets, cell formats,
headers, footers, gridlines to print, etc). Now Save As, and change the file
type to "Excel Template (.xlt)" not (.xls).
Locate your XLStart folder, typically somewhere like "C:\Program
Files\Microsoft Office\Office\XLStart\", and save the file as book. Excel
will add the .xlt for you

Every time you open a new workbook from now on (you may have to restart
Excel first) this template will be used. To revert back to the original,
just delete this file.