@Helen M like Ohsewsimple, I use the longest stitch. I don't loosen the tension though because I'd probably forget to reset it after

. I don't backstitch but I tend to use a similar colour thread to the overlocker and generally don't bother to remove it afterward as it's trapped in the overlocker seam. I machine baste my jersey garments a lot, especially sleeves, as then I can overlock with confidence!