How can I return injustices to their owners when I have forgotten from whom I stole and what amounts I stole?

What was stolen before puberty incurs no sin, as one is not yet accountable. However, the stolen money is guaranteed and must be returned to its owners. If you are unable to reach them or their heirs after making an effort, then give it away as charity on their behalf. If you later find them and they approve of your charity, then you owe nothing. Otherwise, you must repay them. If you forget the amount, investigate and strive to estimate it until you are reasonably certain that you have divested yourself of the unlawful money.