im trying to find peoples earliest ancestor by generations who have more than 15000 anncestors

my methoud is putting the anccestor slider to 5-7 but i cant put the decendants slider to 0 and clicking the person with the biggest little number in the tree icon bruh why do i cant see no children because the slider goes only as low as 1 its rigged to people with more children witch ruins my methouds