Although by this time you ought to be teachers, you need someone to reteach you the basic principles of God’s word. You need milk, not solid food!
KJV
For when for the time ye ought to be teachers, ye have need that one teach you again which [be] the first principles of the oracles of God; and are become such as have need of milk, and not of strong meat.
ASV
For when by reason of the time ye ought to be teachers, ye have need again that some one teach you the rudiments of the first principles of the oracles of God; and are become such as have need of milk, and not of solid food.