I did a dist-upgrade from Xubuntu 14.04.5 to 16.04.2. All went OK except all my KDE apps were uninstalled. Note that I had never installed all of KDE, just the parts that apps needed; the desktop has always been Xfce. While the dist-upgrade uninstalled all the KDE apps, it left all the dependencies installed. So I just reinstalled Ktorrent, as the first of several others that I'll get to later. This went well, but when I launched it none of the torrents that were being seeded before appeared, and none of the many user interface changes that I had made appeared either. Before reinstalling it I looked at the file system and saw ~/.kde/ containing numerous folders, including those for ktorrent, so I renamed it appending .5.21.2018. After reinstalling Ktorrent and discovering that it created a new~/.kde folder (which is why it had none of the old torrents), I shut it down, deleted the new .kde folder, and then renamed the ~/.kde.5.21.2018 folder to just ~/.kde. Then I relaunched Ktorrent, expecting it to come up the way it always used to with all the torrents, but it still came up with nothing.

How do I get it to see the ~/.kde folder and find the Ktorrent settings inside it?

Never mind. It suddenly started working.