Summary report group by year then month

No problem,
You are now grouping your columns by date and then have selected by Month.  But you can group on whatever field you like.

So let's make a formula text field called [MMYYYY] field in the format of MMYYYY

var text MM = Right("0" & ToText(Month([my date field])),2);
var text YYYY = ToText(Year([My date field[]));

$MM & $YYYY

// the above uses formula variables to build the two pieces for MM and YYYY and then I concatenate them together.

// the MM is left padded so that month 1 will show up as 01 (which is necessary both the asthetics but also to be sure that month 10 comes after month 2

Thanks. That is perfect.