If the good karma is strong, the rebirth linking consciousness would lead to another human or Heavenly birth, if the difficult karma outweighs, the rebirth would go to difficult, suffering place, whether the reborn being remembers their past life depends on goodness of mindstates including mindfulness, faith, wisdom, absence of greed, absence of anger, etc. Tibetan Incarnate Lamas are recognized due to their past good habits demonstrated, Tlingit Indians also marked their deceased family who would then be regocnized on rebirth.
Karma the Natural Law of Deeds & Results, turns on the intention of the doer, the only way to relieve of debt, even ignorantly accrued, is by Foregiveness, otherwise when the debts return to one, the payment will be made. Ignorance is a fragile bumper, lasting a a few times, once a person knows better, karma might return faster... intentionally & knowingly causing suffering, will return suffering in kind, unless forgiven..