you need to check if the barrel and see if it is loose even just by a hair if it is then you need to twist it to the point where it is accurate then take out the hold pin for it and reset it
adjust rear sight up for distance
If the sights are fixed, they can't be adjusted. You would either need to replace them with adjustable sights, or else use the "Kentucky windage" method of compensation.
Depends on the firearm.
Via the screw.
By drifting the front sight
Fire one round, note strike, adjust sight to that point, fire again, repeat.
No. It describes the sight picture on the target.
The owner's manual has instructions.
adjust the sight it might be broken
Adv - longer sight radius Disadv - bulky
Best left to a gunsmith
You sight it to a specific range , e.g. 100 meters. Clamp the rifle to a solid object, or use a benchrest. Shoot at a target and adjust the sight accordingly, until the holes in the target zero in to the sight.