Comment 1 for bug 777661

I think I've found the problem. It seems that the settings aren't flushed to disk immediately, so if you log out quickly after changing a setting in gnome-volume-control, then it is forgotten. If you wait a couple of minutes after selecting sound theme before you log out, then it is remembered. But this is inconsistent with the rest of the dialog, because the volume selection in the same tab is remembered regardless. Steps to reproduce:

1) select a new sound theme in the preferences dialog.
2) log out immediately afterwards and log back in.
3) observe that the new theme is not remembered.
4) in the same tab in the dialog, set a new sound level
5) log out immediately and back in.
6) observe that the volume _is_ stored.
7) perform steps 1-6 again, but this time wait two minutes before logging out.
8) observe that everything works as expected.