How can one atone for having argued and raised one's voice at one's mother in childhood, and will a mother's supplication against her son be answered?

The child is not held accountable for religious obligations, as the Prophet, peace and blessings be upon him, said: "The pen has been lifted from three: from the sleeper until he awakens, from the child until he reaches puberty, and from the insane until he regains his sanity." Therefore, there is no sin upon you for what you did before puberty, such as raising your voice at your mother or harming her. The mother is the most deserving of good treatment, kind interaction, and honor. She must be addressed with gentleness, humility, and reverence, as Allah Almighty says: "So do not say to them, 'Uff,' and do not repel them but speak to them a noble word. And lower to them the wing of humility out of mercy and say, 'My Lord, have mercy upon them as they brought me up when I was small.'" Cursing a Muslim is forbidden by consensus, and a forbidden supplication is not answered, as the Prophet, peace and blessings be upon him, said: "A servant's supplication will continue to be answered as long as he does not pray for a sin or for the cutting of ties of kinship." We hope that your mother's prayer of cursing will not be answered because it is a forbidden supplication.