I saw the questions about "Why can J remember everything about K?" and stuff, but there's something I don't get.
J actually changed the past going to 1969 and helping K with the ArcNet.
Ok, so logically, K must remember J coming from future and helping him, because that was what really happened now. That is now the true story about July 16th 1969. J, as a time traveller, came from future and helped his friend K.
So, while all this is logical, why the hell can't Agent K remember J as a time traveller who came from future?