How to line up fabric when doing a cover hem on a garment.
Start by placing the garment wrong side up so you can see the folded over edge of the hem.
line up you needles where you what the hem to be, and use a post-it note, on the bed of the coverstich machine so you can line up the fabric when you flip to the right side to do the cover hem.
Not flip the fabric to the right side and sew you cover hem. suing the post-it note to help line up for a nice and straight hem.