If Lord Brahma sees Krishna appearing every day of his life, every day he is seeing Krishna, but still he forgets. Does he actually experience one day like millions of years or does he experience his days just like 24 hours?

That is a good point. If even though he has such a long life, the whole life of the universe, he experiences his years as we do ours, his life would be no longer than ours. How could it be that someone is Brahma but they experience their life as being as short as we experience ours? That does not sound plausible to me because even though time goes at different speeds at different places, it must be the case that if you were Brahma, you would experience life as being much longer. I think that if your day is long enough, it is plausible that. within a day, you would forget something. Brahma’s day is four billion, three hundred million years. That is a long time. That is enough time to forget. It could also be yogamaya.