Young Adeniums are thirstier, so they like being watered often. But that being said, I find your container too big for the plant, so it may be rotting the roots below slowly, hence new leaves are not growing well. It likes as much light to direct sun at this time of the year if possible in summer, but got to be kept well watered, and grown in a very gritty, well draining media.
Wide mouth containers are good, but must be shallow.
