It seems that Toad for Data Analysts will allow me to create a Custom date format such as dd-mm-yyyy (Tools | Options | Environment | Grid. On the RHS: Font : and Date and time format).
Although Toad for Data Analysts appears to like the format, when one see the data grid results, the outcome is 12/17/1980 12:00:00 AM .
It seems to default to DateTime format Default: G
For this format, captialize the months value to: dd-MM-yyyy
If the Months parameter is capitalized (dd-MM-yyyy), the DateTime format works properly with dashes.