Once again I see the NASB falling into the trap of modern translators. They just can’t let the Bible speak for itself. They are afraid to let people wrestle with what God said.
(Proverbs 15:23 NAS77) A man has joy in an apt answer, And how delightful is a timely word!The KJV is quite literal. The phrase “apt answer” in the NASB is a paraphrase that it acknowledges in the margin. The margin says it literally means “answer of his mouth” which is exactly what the KJV says. I would make it even more literal and say “mouth (6310) answer (4617).”
The KJV makes it clear that this is a potential that can be achieved, not a promise. Do you have a mouth of “joy” (8057)? I think it is obvious that Solomon assumes your mouth will be guided by an informed mind and a changed heart.
So? Start on the inside. Let grace do its job on your heart. Then apply it to what you mouth does and experience a new world.