Comment 10 for bug 360147

I've been having some of the same problems as the rest of you. When I started making changes to the event sounds in system->preferences->sound: sound tab, my theme was blank, then changed to "custom." None of my settings would stick, and the preview buttons would only preview the default sounds for each item. I did not experience jlaroche's problem of only the login event sound playing.

After much google-searching, I found https://bugs.launchpad.net/ubuntu/+source/libcanberra/+bug/347537, which describes a workaround where you have to change your theme to "ubuntu" to get settings to stick. My sound changes now stick, even after reboots and logouts. Hope this works for everybody else...

I think this is a related bug: https://bugs.launchpad.net/ubuntu/+source/gnome-control-center/+bug/277203