There are two parameters of crucial importance to chenille work – needle height and stitch length. Chenille design frequently involves juggling these two parameters to achieve the desired effect.
Generally speaking, needle height controls the height of the loop formed by the chenille machine when it is sewing moss stitch. The needle height setting has less effect on chain stitches though it does affect width.
Stitch length has more of an effect on chain stitching. This value determines the size of chain. It also affects loop height, though for moss stitching, it is easier and more accurate to adjust needle height.