Make your own Excel templates
If you reuse the same styles, templates could save you time
If you reuse the same set of formatting styles in Excel frequently, turn them into a custom template so that each new workbook will start with that formatting.
Begin with a blank sheet; enter the data and cell formatting that you want to apply to new workbooks. Use File | Save As and select Template (*.xlt) from the Save As Type list.
By default Excel will invite you to save the template in the Office Templates folder. But to define new default styles that apply for all new workbooks, you'll need to create them in a template file called book.xlt and save that in the XLStart folder.
The procedure isn't difficult. Open a new workbook, use Format | Style to amend the styles, and save the result (File | Save As) under the name book.xlt. The file type should be Template (*.let) and the destination should be your XLStart folder.
You might need to use Windows Explorer to find XLStart - if you used the default location when you installed Office, it will probably be C:\Documents and Settings\[yourname]\Application Data\Microsoft\Excel\XLStart (for Office 2003) or C:\Program Files\Microsoft Office\Office\XLSTART (for earlier versions).
Subsequently you can open that book.xlt file and make any additional style changes. Provided it's saved back in the XLStart folder it will be used for all new worksheet files.
Existing workbooks won't be affected, of course, and their own styles will continue to apply to them (the toolbar buttons will work as before). To apply the new set of styles, open both the old workbook and one that uses the new styles: go to the older file and select Format | Styles | Merge: nominate the newer file and click OK. That will update the styles in the older file.