Headphones

When I listen to music on my computer, if I am listening to the speakers and plug in the headphones the sound doesn't stop coming out of the speakers and no sound comes out of the headphones.  So I have to remember to plug my headphones in before I turn on my computer or restart my computer if I forget.  Today, I was listening to music on my computer and had my headphones on. After many hours of music, I realized that I was listening to the music through the speakers the whole time and there was no sound coming out of my headphones.