I just use the pressure foot to measure mine with. I keep all of the seems the same size that way. :-D

seeing I'am not the only one with the 1/4" problems. I'am going to try all of the answers. thank you

Just to add my two cents! I took me forever! Is the feed dog tension tight enough? sometimes fabric slips around if the dogs can't catch the fabric. If you can slow your machine speed down, do it! There is no need to be in a hurry. Use a piece of scrap 'rabbit' fabric to start the sewing for your piecing to follow and use any thing you can devise to act as a stiletto at the end of piecing to hold the fabric on the 1/4" mark right off the fabric. I also use the post-its and I use masking tape to hold it in place. Keep on working at it! Also the index card trick is a great one and it works! And Press not iron the seams!