Microsoft Excel - Customize Excel's Default Workbook (97/2000/2002/v. X/2003)
If you'd like certain settings to always be applied to new workbooks, you can override what file Excel uses as the basis for new files. All you have to do is create a special template file and save it in your XLSTART folder.
Before you actually save the file, you need to identify where your XLStart folder is located (or your Startup: Excel folder if you're using a Mac). The location varies depending on both your Office version and operating system, so your best course of action is to use your operating system-s Find or Search feature to locate the folder. You may actually find multiple copies of the folder, depending on whether your system incorporates user profiles--choose whichever makes the most sense for your needs and make a note of its path.
Once you have the folder path, configure a workbook as you'd like and then save it as a template. To do so, choose File | Save As from the menu bar. Next, choose Template (*.xlt) from the Save As Type dropdown list (the Format pop-up menu on a Mac). Using the Save In dropdown list, locate and open the XLStart or Startup: Excel folder. Finally, change the File Name setting to Book.xlt (just name the file Workbook on a Mac) and click Save.