DSV has Date YYYYMM, but in Cube it's YYYY-MM-DD

I've got a DSV where I make a new YearMo date column off another full date column with a CONVERT(VARCHAR(6), actvt_dt, 112) AS "Year Month"
I read that date column of YYYYMM into the tab cube, and  it shows up as  YYYY-MM-DD. I've tried to u