You can change your child's password on your parent account.
- Click Settings (in the top blue bar)
- Click EDIT in the Children box
- Click reset next to their current password and Sumdog will change your child's password
However if their account is also linked to their school, you would need to speak to your child's teacher to reset their password.
Always remind your children not to share their account login details with friends and to log out of their accounts when not in use.