Simply lift the pedal, then insert the button underneath, and proceed to sew the jeans.
Another trick that you’re able to try is when hemming a silk dress.
Fold the neckline in half, then find the midpoint of each side and sew small darts on them.

Image Credit: Downtown Tailoring via YouTube
Set the length of the stitch to maximum, then release the tension, and sew.
Pull the thread a bit to lightly gather the neckline.
*Thanks toDowntown Tailoringvia YouTube for all images used here.

Watch her video tutorial below for more alteration tricks!
3 Alteration Tricks To Make Sewing Easier
