SUMMARY
My default audio device is ignored. 

STEPS TO REPRODUCE
1. Set default audio device to one other than the one that is selected after a fresh installation.

2. Open an application and start playing audio (e.g. Clementine, Vivaldi browser)


OBSERVED RESULT
Application begins playing through the original default device and not the newly selected one. By selecting a different default, then selecting the desired default all playing applications will then begin playing through that device.


EXPECTED RESULT
Selected default device should play audio.

SOFTWARE VERSIONS
(available in About System)
KDE Plasma Version: 5.14.0
KDE Frameworks Version: 53.51.0
Qt Version: 5.11.1

ADDITIONAL INFORMATION

Certain applications will seem to retain settings once they are selected in the "Applications" section of the Audio settings. e.g. I can open Clementine and experience the bug, but if I set it on the application page it will start playing through that device even if the application is closed and reopened. Other applications lose this any time that the application stops playing long enough to disappear from the "Applications" settings page. e.g. Vivaldi can have a video playing and will default to the incorrect device. If it is set on the application page it will work fine. If the video is paused for a few moments and the application output disappears from the "Applications" page it will then start playing audio back to the incorrect (original default, before being changed) output device and needs to be set again every time the audio stream is restarted.

Behavior is consistent across multiple distributions. Kubuntu 18.04.1 does not appear to have this issue, but Fedora 28, Manjaro KDE, and now KDE Neon do.

Possibly related to Bug 396296 as I end up often seeing similar issues as described in this bug, but am not reporting on the same thing.