One strange behavior in Android that you’ve likely never noticed on Android relates to incoming text messaging sounds. In order to adjust your incoming text message notification volume, you normally need to adjust your notification volume rather than your incoming call volume. However, a text message is more related to your device’s “phone” functionality than, let’s say, an incoming Hangouts notification. Therefore, it makes sense to have your ringer volume adjust your incoming text message sound instead.
The reason for this behavior is that incoming text message sounds are processed through the notification audio stream, rather than going through the ringer audio stream. Thus, changing ringer volume does not affect incoming text messages. Thanks to XDA Senior Member OXINARF, however, this is no longer an issue.
OXINARF’s modification comes in the form of an Xposed module, so naturally, you’ll need to have XDA Recognized Developer rovo89‘s Xposed Framework (thread) installed. After that, simply install and activate the module, reboot, and enjoy your slightly more logical volume management. While originally intended for the Samsung Galaxy S III, the developer says that it should work on pretty much any device.