Karen, you may be interested in some of the posts in this recent forum topic: [url]forum/i-need-quilting-related-advice/4259-crayola-washable-markers[/url]
My best advice would be to soak the fabric in cool water, with NO DETERGENT, over night if necessary to see if the blue pen marks disappear.
If heat has set the marks, you may have to live with them.