Hi Pipco,
Open a new, blank workbook.
View | Zoom | Check "Custom" ! Enter 123 as the custom value | Click OK
File>Save As
Select Template (*.xlt) in the 'Type' dropdown
Name the File "Book.xlt"
In the 'Save In' box, navigate to your XLStart folder
Subsequently, all new workbooks opened using the New File toolbar icon (or
File | New | "Workbook"), will be set to the revised zoom setting.
If necessary, perform a pre-emptive Windows search for the location of the
XLStart directory.