Hey if your light is already max height then they are definitely outgrowing your space. There are 2 options here. You can cut the tops off or do some supercropping by taking the stem where you want to bend it and gently roll it between your fingers until it softens up enough to bend it over. You will have to tie it or support it for a few days after bending until it hardens up. I would supercrop rather than topping because you wont lose any buds this way. I have had to supercrop a few of mine and it ended up helping in the end because all of those buds that would have been lower on the plant ended up fattening up just like they were all tops. Hope this leads you in the right direction.