On multiple computers, I have an issue where Skype won't ring to my desktop speakers.
I can go into the audio settings and select my desktop speakers under "Ringing", which works for a short while, but by the next day, or within a few hours, it switches back to "Use selected speaker".
When it switches back to Use selected speaker, it rings on my USB headphones that are specified in the Microphone and Speakers settings. The headset works fine, but the problem is that I can't hear the ringing for an incoming call once Skype changes the destination for the ringing.
I've had this problem for a few years on three different desktops and haven't figured out a solution.
This thread appears to discuss the issue, but they believe it is a loss / change of functionality with a new version--but I've had this issue for 3-4 years.