well if you feel there not under watered then give them a little n
that should solve the yellowing if not could be ph issue hell you could be
over watering with a nute issue idk.
i would let one dry out and another i would drench the soil.
the first couple grows i would say you learn most when it comes to general cultivation
remember no one knows your plant better than you because you take care of them
so take online advice with a grain of salt and learn from your own exp
not just others and you my friend will then officially be on the ganja journey.