If you modify a column from a char datatype to datetime, smalldatetime, or date, you can neither specify the order that the month, day, and year appear in the output, nor specify the language used in the output. Instead, both of these settings are assigned a default value.
However, you can use set dateformat or set language to alter the output to match the setting of the information stored in the column. Also, SAP ASE does not support modifying a column from smalldatetime to char datatype. See the Reference Manual: Commands.