usually the bottoms will yellow and thats normal but if its towards the top you have an issue with nirto usually not enough if you could post pics i could get a better idea of whats what
as long as its pretty dark it shouldnt be the issue all i did for mine was filled up a few bottles with water and popped them in there took about a week and they both had only a few roots but i planted in soil and they took no problem
as long as their autos it really doesnt matter how much light they get from what i hear you can run a light on them 24/7 but i havent tried it their pretty hard to stress out