Most birds will learn to speak more readily if you almost sing to them the phrases or words that you want them to say. The more excited you seem as you verbalize, the more they will want to repeat. Repetition doesn't work. Monotonous recordings don't work. Saying the appropriate thing at the right time with inflection in your voice works.
Some birds also take longer to learn to talk than others.
Watch their eyes as you speak or sing. If they dilate and you see their beak open and their tongue move, they want to learn. We have a 16 month old sexed female Congo African Grey. She has a stable tempermant and is not nearly as neurotic as greys are often described. My question is in regards to her speech.