I found the problem: my configuration files came from a slightly older version of Audacity. I'm running Kubuntu 14.04, and I assumed that I had the latest version of Audacity since I had downloaded it from the official Ubuntu repositories. A few versions back, the recording meter and playback meter were both on the same line. I suspected that there was a version problem, so I downloaded 2.1.2 from the Audacity repository. Though I had the latest Audacity, I still had the older configuration files since the download didn't replace them.
I deleted my configuration files, restarted Audacity, and now everything is in sync.