On the subject of atoms.

On the subject of atoms. It is interesting to note that the atoms in our bodies are replaced numerous times throughout our lifetime. The atoms in our brain are no different. We do not have the same atoms now as we did when we were children, for example. This raises various questions pertaining to reality, consciousness, memory, etc. This suggests that we are not the matter of which we are made, for our matter is constantly replaced. Where do thoughts reside, and memory especially, if our atoms are replaced many times? If we do not have the same atoms throughout our lives, than how do we retain memory? Indeed, how do we claim to be the same person, if our matter is different from our selves in the "past"? This seems to imply that our "self" is not located in the physical, for the physical matter changes while our personality and memories remain. You would assume that if all the atoms in your brain would change, then the makeup of the brain would change, yet we manage to retain an identity, thoughts and memory.