okay here comes another question
should we be locking out our knees when we're doing squat?

Am doing front squat today,1 huge fella come to me,and ask me to wear belt for protection,and ask me not to squat heavily(yea that time i was struggling at 140 lbs+20kg olympic bar, front squat for 5 reps)
According to him,I am not supposed to lock knees when I am standing up,I should control the movement slowly and maintain the muscle tension there.

and he did pointed out I tend to 'bounce' when I am standing up,which is stressing more to the knees.it will hurts the ligament and I will be regret after 3-4 years.squat should not be too heavy as I am not competing ,why rushing ? yes I admit it,when I am standing up I tend to bounce so the lift will be easier.but I never realized thats a cheat form and could be potential harm to my knees.

Well,kinda speaking,he's much bigger than me and least years of experience,so now...I always think that squat should be go heavier,or i should follow to this guy advise? dont lock out,go slowly..

and my feel left knees knuckles cracking when I am doing front squat..which I recheck my form,its should be shoulder stance,foot pointing outwards,hips go downs,knees not over toes....it is not pain but feel weird....

There are not over than 5 people squating in the gym room,and only 1 people who doing deadlift,thats me ! none-of any instructor there,which I barely cant find a big bodybuilder and ask for the skill helps.

Someone enligthen me , I am confused,especially the knees cracking part seriously bothering me,and I might not want to harm my knees,I know squat is way too important,but if I am doing it wrong end up this might be my last chapter of bodybuilding.I did googled,but too many version there ,confusing which 1 to follow.

yes bro,haven seen you for a long time,if I am not mistaken you should 1 of the squaters in Priority too
Sadly is,no ones with nice leg development there.at least I haven meet anyone.
His legs??...
erm...I would say Ok...but its a lil bit tiny compare with his HUGE upper body.and I did see him squat before,
narrow stance then goes 45% degree,but I not sure there is any partial movement for those big guy so I dint dare to judge its a wrong form.

there are no superior legs' development in the gym.sadly say that  neithers  deadlift nor squat
bench press ,military press,barbell row.. yes there are alots out there

Yes I dont bounce like a rabbit,I was like go down slowly..then explode up...end up might locking the leg,but I dint felt any back pain from front squat.

my lower body is overweight compare with my upperbody.

Yea, a litre of apple juice burns away at least 500 calories. No shit.

But the volume 

Close to 40 sets total for arms.