Top be honest, they "use a file" faction is probably right - settings files aren't really there for data and they aren't really good at it.
Using a file isn't difficult, and particularly with something like a list box it is the logical way to do it. It's even pretty easy, File.ReadAllLines will return each string separately in an array for you ready to load into your listbox, and File.WriteAllLines will save them back for you ready for next time if they get changed.
This will show you a good place to store the file:
Where should I store my data[
^]
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