Corner help please

I have been helping bind some quilts for a church group for donation .. only a couple of us can sew. The quilts are basically a front fabric, a backing with a batting in the middle then they are tied together with yarn. Then I'm asked to sew a binding edge on them. We don't have matching/ complimentary fabric to put a regular binding on all of them. So I had this idea .. first I cut all layers even and then folded back the backing so I could cut just the front & batting 3/4" shorter, I did this on all 4 sides. So now the backing is 3/4" longer on all sides, I folded that (3/4" width) in half and then down on the front and stitched it down thru all layers with my sewing machine (I like to use decorative stitches for this)...It looks okay and worked pretty well except on the corners .. they should look a little better...I cant seem to fold them correctly to stitch them down. So If anyone has understood what I tried to explain, any helpful ideas I can use are very much appreciated. thanks tish