customer billing


I am having trouble with a template I made for my monthly customer billing
statements, I cant seem to save it for multiple customers. I've saved it as
..xls, template, workbook,spreadsheet, etc... When I add or update customer
data it will save the information and then my "original template" is gone. I
knlw there has to be a simple soultion.. I just can't get it for some reason.

Thank You,