When setting the preferences for the short date string, the Day of Month does not include the trailing 0. How can I change this?
I think I found the answer myself (at least I have what I want):
System Preferences... > Language & Region > Advanced... > Dates
What I expected was the option to open the Day of Month drop down and select an option with a trailing zero, just as the digit Month allows:
But I don't see that:
So when my Googling came up empty, I coincidentally copied the contents of the Short field
into a text editor and this is what I found:
So I got the bright idea of pasting "yyyy-MM-dd" into the Short date field and seeing what happens. Sure enough, worked like a charm:
This also worked with getting the trailing zeros in Excel on the year:
Use/copy the Swedish locale for date and time. It follows the ISO-standard.