Just for grins: What happens to stitch length when you change it on regular pieces of fabric? Does it change?

What batting are you using? Does the sandwich travel easy through the machine, or do you have to pull and tug?

I agree with these questions. Make sure that the machine stitches normally on two pieces of fabric first. If that's okay, then I wonder if the batting is too thick for the machine to handle.

Are you supporting the weight of the quilt? Is the quilt bunching up so it's not moving freely under the needle? My quilting area is very small and if the quilt bunches up against the back wall it doesn't move freely and my stitches are very small. (hope that made sense) I also use my ironing board to help support the weight of the quilt on the side by me so there's no extra tension or pull on the quilt. This also affects the size of my stitches.

Take that piece out and try a regular piece of fabric to see if it is the machine or the bulk of the fabric causing the tiny stitches. If it is the machine it is possible that the bobbin is hanging up somhow. I have to ask, did you put the foot down while changing the tension? If you didn't, it didn't change a thing. It has to be down to change it.
Also, check the way the thread is being held all along the line of the machine. Sometimes it accidently gets stuck somewhere, or the tension disks need cleaning with apiece of dental floss. All else failing the machine is just not happy with the density of the quilt. Oh one more thing... open up the machine and clean out any threads hanging around that don't belong there.

I was having a problem yesterday with little tiny stitches. I was so frustrated. I turned my machine off and when I came back and tried it again, it worked fine. Why? Who knows.

It was the quilting fairy. She waved her magic wand over your machine and fixed it.

Are you using the walking foot with the feed dogs dropped? It could be that the quilt sandwich isn't feeding properly. Make sure the dogs are up.

Oh, and something I'm always doing--Once I've positioned the quilt sandwich to begin sewing, it's often so thick that I forget to lower the presser foot bar. You'd know if you were doing that pretty quick though...the bottom thread is all loopy and the machine complains.

Yes, the stitches DO change with 2-4 thickness of fabric and the batting is the thin batting that JoAnn's sell by the yd off the bolt. The sandwich does not travel easily, I would stop about every 4-6 inches and straighten the fabric and adjust the weight (it is just a lap quilt) and I did make sure the presser foot was down! Maybe the machine just cannot accomodate the sandwich. I have done a Quilt as you Go with flannel batting with no problems.
Thanks for your help>>>always enjoy your comments on the blog!!

Yes! Supported the weight and adjusted every 4-6" of sewing. I'm drawing the conclusion that the problem could just be the weight not allowing the sandwich to move. Thanks for your help!