If you haven't heard of SoundSwitch, its an app for windows that allows you to switch sound output/input devices with a keyboard shortcut. I've made a similar app for linux, but I cant get it to work properly. The majority of the app is done, and if you want to see the full code, its here: <https://github.com/boskobs/sound-Source-Switch-4-Linux>
Bellow is the part responsible for applying the changes:

```
   os.system("pacmd set-default-sink " + str(nextindex))
   output = subprocess.getoutput("pacmd list-sink-inputs")
   for item in output.split("\n"):
      if "index:" in item:
         inputindex = item.strip().replace("index: ","")
         os.system("pacmd move-sink-input " + str(inputindex) + " " + str(nextindex))

```

It changes the default sound output device, and transfers all of the current apps to that device. The problem occurs when I exit an app and switch the output device. Next time I start that app, the device it outputs sound to is the old one that was active before the switch. How can I make the new default output device really work as a default?