Ikea Nordli drawer assembly

Hi who can give me tips for assembling the drawers for the Nordli dresser. What are the plastic holders used for that are attached to the adjustment screw at the bottom of the drawer? And how do I level crooked drawers? Looking forward to your tips :)

Hello,

You can adjust the fronts in height. The plastic parts serve, as far as I know, as protection against accidentally lifting the drawers upwards.

Regards,
IKEA-Freund

Thank you! The puzzle is solved..