Krsna has explained that Paramatma is everywhere and in another shloka it is explained that He is present in everyone's heart.

This Purusha is superior to the other two.

And then Krsna says that He is the Supreme Personality of Godhead and is the Purushottama. He doesn't declare it directly but very humbly He says, that in the three lokas, the Vedas and the sages have declared that I am the Supreme Personality of Godhead. Therefore I am Purushottama.

This is a nice way of presenting. Right? Sometimes suppose if we are a team leader than we may present ourselves saying, My team members think that I'm a team leader. It is a nicer way to present yourselves right?

Here the Lord is explaining how He needs the Vedas and the Brahmanas to present Himself as the Supreme Personality of Godhead.

From these words we can understand the Lord's humility and greatness. Srila Prabhupad has explained all this very beautifully. Srila Prabhupad has always explained how Krsna is the Supreme Personality of Godhead and Lord Krsna has said that the Brahmanas help Him in presenting Himself as the Supreme Lord.