Help, leaves are going yellow

I am a first time grower and i am having some problems, the plants are about 2 weeks old and the leaves are going slightly yellow in some points, also the plant seems to be a bit top heavy, i water them a little about once a day depending on how dry the soil is. Any ideas as to why they are yellow and why its top heavy? Ive added some pics to help

your plant looks a little lengthy so there might not be enough lighting. and as for the leaves place a fan by your plants for better air flow, i did that to my crop and the leaves looked a lot greener and healthy, your stem will also get a lot stronger. are you running a fan right now?

yeah ive got a desk fan in there and a 400w lamp about 30cm away from them

Over watered,over fed,possibly you stuck that stick through what roots it does have,400watt lamp is to close to such a small plant.
Flush it through with clean filtered water and then let it dry out a bit,move the lamp at least a foot away from the top and remember that if you stake such a small plant how can it wobble in the wind?

Just had another look at your pic and i also reckon that you should repot it right down to its first set of leaves and get rid of the stick.

Ive re-potted them as low as i can without destroying the roots, it has made a difference but if i dont prop them up they lean over proper bad, any suggestions?

im using a 150w hps and having the same yellow leaves at like 9 days old my plants arent as big as that, i got one thats floppy two that are a bit yellowish on the tips and one that looks nice. its the first time ive grown and i hope ive not fucked em up hahahah.