have skinny plant. want bushy plant. ideas?

i have a purple kush plant indoors that is growing really long and skinny. I dont understand why because i trim it properly, the light is positioned properly, i have a strong fan on it. the odd thing is my northern lights plant that is right next to it has a really thick stalk and is very bushy. any suggestions on how to fix this?

I'd re-pot the plant, burying up to 1/2-2/3 of the main stalk if possible. After that, I'd FIM it. Just my opinion though.

rotate the pots, maybe 1 side of the room gets more light then the other.

Top it and force it too grow outwards.

proper lights?, trimming? if all else fails tie it down and give it appropriate light.

super crop it man so start pinching till it gives out on each node thats you best bet and when its pinched is where it will start to swell it as it heals bro

Some pics would help get you some better answers.