Prior Post Widget

Today, without me doing anything, the “Prior Posts” widget disappeared from my sidebar. And when I went to re-add it, the appearance of that widget was different than it had been before, and different from all the other sidebar widgets. Moreover, the option to change the title of the widget does not appear in the customizer.

Please help. I want it back like it was.

Thank you,
Kevin Lapp

The page I need help with: [log in to see the link]