Why Don’t We Remember Our Past Lives?
Our current personality (our Ego) is only part of our whole being (True Self).
When we come to the earth, we (our True Self) decided which part of our personality will be present in this life. If this part personality is the Sea, than our True Self is the Ocean.
We are living in a material world, where time exists, that is why we can say our past or future life. In the reality these are illusions. We experience time to keep the focus on our current life. However in your childhood you were much closer to your True Self, and you remembered much more on who you are.
The more we take part in the earth life, the more we may lose the connection, the more we think that Ego is all that exists.
In every life you are able to express yourself, creating and achieving things, that the most describes your True Self.
Why we lost our past life's memory?
Because of the game. You could experience the now in deeper level with this disability. Imagine if you could remember on all your lifes, would it be matter if someone die? It would be much different, less stress at least ☺.
It was a brave decision to forget everything, but it was Your decision.