Sound settings stopped working

I have speakers and headphones that I use with my computer. It used to be set up so that the audio output would go to my speakers unless my headphones were plugged in. If I plugged them in, and audio going to my speakers would be transferred to my headphones. However this stopped working for some reason. Now I still have my headphones as my default audio source, so when I plug my headphones windows changed the default audio output to the headphones, BUT does not transfer current audio output from the speakers to the headphones. How do I fix this?