hi, Joseph !

I require to use brackets (0) for all credit amounts in my spreadsheets
and use the formatting option to alter -0,000.00 to (0,000.00)
in each individual spreadsheet.
How can I retain the above format (0,000.00) in Excel number format list permanently
together with the other number formats. ?

save a workbook (w/ only one worksheet) as template (*.xlt) with (all of) your number formats:
- book.xlt will apply to any new workbook
- sheet.xlt will apply to any new sheet added to any open workbook

note: if you need this availability from scratch (opening excel)
you will need to "move" the templates into your application startup/alternate path folder
the alternate path is stated in (menu) tools options general ... open files in ...

if you *just* save as template, you will need to *choose* from template wizard

hth,
hector.