Just looked at a pic of your machine - is this the display? [ATTACH=CONFIG]431920[/ATTACH]
After looking at the display shown - it shows the stitch width with a arrow to the left and the stitch length with an arrow up and down. So the stitch width is probably the left/right arrow buttons on the right below the display and the stitch length are the up down buttons on the right below the display. BUT I am just guessing here.