Trick to get New Skype for Linux working with alternate Microphone
It took several false starts before I finally figured this out. The new Skype for Linux (2017) is no longer a separate dedicated application, it is a Chromium web app. This version of Skype has no options for changing default microphone! But, here's the trick...
Start Skype.
Start your Pulse Audio Volume control.
Select the Recording tab. Right now, you will NOT see Skype listed as an application.
Start making a call to the Skype Echo / Sound Test bot.
Now you will see Skype show up as Chromium.
Quickly, while the call is just starting, change the input setting from the default, to your desired device.
Now it should work!
I did this with OpenSuse 13.2 btw.