Your parents are your guardians from when you are born and manage your finances, among other things, until you turn 18. As an adult, access to your bank account is transferred to you. However, if you are unable to take care of your assets and interests, your parents may continue to manage your finances. It is therefore advisable to take care of matters related to guardianship, power of attorney and access to accounts in good time before you turn 18, so that access to your funds is not completely cut off.
Read about guardianship and continuing power of attorney on the Suomi.fi website(Link leads to external service)