How can we forget anything that we have paid attention to? Is that making an event in consciousness that has occurred dependent on personal omission? In the view of Bergson everything remains 'out there' requiring only retrieval by a focussing of the brain. Using a holographic analogy Dr. Stephen Robbins writes of a reconstructive wave which requires a similar wavelength to the original conscious event. The idea of the brain scanning the contents of the brain itself is rejected. The loss of memory due to brain damage is not due to the destruction of storage there because in time the reconstructive aspect of brain function can pass to another area of the brain. Stroke patients can recover language and memory returns.
In his simpler formulation of the brain's function Bergson likens it to a reducing valve. We screen out the dross and retain only the highlights so even the events we think we are attending to are chopped up. Forgetting is a good thing, the totality of the flow of events would overwhelm us. Living in an extended intuition of duration requires a special environment like a monastery or an ashram or a well appointed cave.