Our past lives memories will sometimes come to us very clearly, allowing us to see the nature of our soul’s journey lifetime after lifetime. Children are particularly good at recalling their soul’s memories. You can read about this phenomenon here, but there are many books and articles on the subject:
10 Amazing Things Kids Have Said About Past Lives
Our short term-memory is related to the mind, as opposed to the soul. This is a very fallible memory bank and we can barely remember what we did two weeks ago on the same day. That is not a soul connection. But memories of lessons we learned, soul mates we encountered, suffering and joy we underwent in a different incarnations, are all keys to understanding who we are in this life.