I find using lists for data validation very handy, but also very
confusing. This is what allows me to have a dropdown containing
possible cell values. Defining and altering these lists seems very odd
and awkward.

I managed to get a set of lists working, so that they show in the
dropdown. However, I needed to add an entry to the top of one of the
lists. So, I added a row before the first one, but when I click the
dropdown arrow on cells referencing that list, it still shows the old
list. What do I have to do to get the cells to use the new list?