A very dumb Access question

Hello,
Sorry for this one, but I can’t remember how do do this. I can’t get my date/time field to change from standard short date to a date structure that allows only month and year entry (mm/yy). I have used the input mask wizard to create a new input mask and when I try to enter a date that is month and year only it gives me the month and 4th day of 2004 (example 1/4/2004) as the date. What am I doing wrong?

Thank you in advance for your help