The 'Use 529 accounts to fund Pre-College Education goals' setting can be found within the Gear Icon > Settings > Methodology tab of each client plan:
This setting allows you to specify if 529 accounts will be used to fund Pre-College Education goals. By default, this setting is checked.
When checked, up to $10,000 of 529 funds will be used to fund the pre-college education goals each year. If unchecked, 529 accounts will not be used as a funding source and will be reserved exclusively for college goals.