Quilt Lady,
Can you post a picture of your machine screen? There is a "lock" button you may have accidentally hit. I use it to prevent accidentally changing settings.
If your machine has a memory function, you can save your favorites (stitch, length and width) to a memory pocket for use again later. Do you have the manual for your machine? If so, Check for the lock button picture. It looks like a regular pad lock.
The other tip is to check your preferences pages. Scroll through them and check each setting. You want the one with the black box around it for default settings.
Hope that helps. Post back here and we may be able to help trouble shoot for you.