I have two Mac OS X machines, both running Microsoft EXCEL 2011.
One uses a comma to separate function parameters, e.g:
Yet my work machine uses semi-colons, e.g:
How and where can I change this?
The Excel 2011 function argument delimiter seems to be tied in to the region settings of OS X. I have been able to get a comma as argument delimiter in Excel by setting the region of the machine to the US or to the Netherlands. (It was originally Swiss-French)
This obviously also changes the usage of the komma and the dot in number notations and the convention for showing dates. These I was able to customize all back to my original preference via the customize buttons, whilst leaving the new argument delimiter behavior intact.
For Mac OS X 10, the Advanced... settings in Language&Region allow you to choose the Decimal separator in 2 places, for Numbers and Currency.
If comma is not set in any of the Decimal separators, then it is free to be used as the "list separator" in Excel. Please note the whole Excel app needs to be quit&restarted for the change to take effect, not just closing&reopening a file.
The list separator applies to formulas as well as for opening CSV files.