When you repot them, I suggest planting them deep. Up to the first set of leaves. Are they staying in that tiny box the whole grow? They will never fit
This is over watering.. Yellowing and the leaves drooping down means that the plant is wet and sad. The leaves on a marijuana plant should be reaching for the light.. They should be firm and the points should be reaching, not droopy and depressed. Never water on a schedule. Learn to know...