Setting audio output device works poorly

[spike6479]

Hi there,
I'm running win7 64 bit. This problem occurs with both 64 and 32 bit versions of smplayer (mpv and ffmpeg). I have two audio devices on my system (headphones on one, speakers on the other). If I try to fix smplayer on one device, it doesn't stay fixed if I change the windows default device to the other.

For example if I have the default device set to headphones and I set the smplayer to use headphones, all is fine. If I change the default device to speakers, then restart smplayer the sound is directed to the speakers, even though the output driver still points to headphone device. In fact if I set smplay to output to the speakers at this point then the sound goes to the headphones?!