For K4 clones, it's essential you don't overtighten any parts. To close the juice channel, if the drip tip is facing your left, turn the lowest part towards you until it stops. Then only you open the top juice cap. Then after you fill, reverse the action. To open the build deck, it's recommended to use a suitable size Allen key, insert it into one of the side air hole & gently open it. Again, don't overtighten.

About the bottom air hole, you gotta screw out the 510 connection pin & adjust accordingly the air hole pin. Each time you make a turn, give it a suck to determine the air flow that you prefer.