the option is greyed out when installing kde on a gnome-only installation: KDE > Audio Volume Settings > Audio Volume > Advanced: "Automatically switch all running streams when a new output becomes available. Requires 'module-gconf' PulseAudio module" > is greyed out and disabled after a kde install. this causes the problem that only speakers are enabled by default, and after connecting earphones to the audio jack there is no sound, you have to manually to to settings and change the output device. Most people won't realize that immediately which can make users think that hardware is not supported or proprietary drivers are missing. Please fix this.
Created attachment 112477 [details] module-gconf missing on fresh kde install
I fixed the greyed out option to make it tickable installing the following package and rebooting: pulseaudio-module-gconf
Created attachment 112480 [details] pulseaudio-module-gconf-doing-its-job.png
Fix this because some users may thing there is a problem with the audio driver when they connect the earphones and there is not audio on them. In Microsoft Windows it automatically switches.
By the way, once the option is enabled, disconnecting and reconnecting the headphones, automatically switched between these two: - "Analog Surround 4.0 Output" when disconnecting the headphones, which makes the speakers work. - "Analog Stereo Output" when plugging the headphones to the computer jack port, BUT there is no sound on them because it should select "Digital Stereo (IEC958) Output" instead. This is probably another bug.
Reported: https://bugs.freedesktop.org/show_bug.cgi?id=106429
Running pulseaudio-module-gconf-11.1-18.fc28.x86_64
I don't really see what is the issue here. It clearly indicates that you need to have module-gconf PulseAudio module for that option to be available.