I've been a widow for 8 yrs now - why does TT ask me every year if I have a custody agreement with my child's other parent?

I've been using TurboTax every year to do my taxes. 
I've been a widow since 2017. After the first few years of being able to file as Qualifying Widow, I now file as Head of Household. 
But every year for the past 4-5 yrs at least, when adding detail for my children, I get asked if I have a custody agreement with my child's other parent. And only it asks the question for my youngest the past few years. Maybe cause my oldest I can no longer claim as a dependent?? 
I always just answer no to the question, but I'd love to understand why it's asking me that question in the first place. 

I am my child's only parent!