drop box navigation

The drop box at https://rocketllama.com/ongoing/ has things listed out of order. I can’t imagine why Special Editions got listed between #136 and #137. That’s neither chronological nor alphabetical. How do I control the order of items listed?

A related question: How do I make the list hierarchical? We need a clear distinction between those that fall under Modern Webcomics and those that fall under Original.

Thanks.