Why both headphones and speakers are active on my windows 8.1?

When I plug in my headphones into my laptop, speakers remain active. I have mute speakers mixer so they don't play sounds when headphones are plugged in, but the problem is, some of applications only appear in the speakers mixer and I can't hear them over headphones. I didn't have this problem before.

I already had set headphones as default device on playback devices settings, but that was no help.

Currently I just disable speakers to get all applications sound over headphones but doing this over and over is annoying.

Did you install the drivers for your audio card? It is also possible that your laptop is not picking up the jack when you plug it in and not mutes the speakers.

Try setting the headphones as BOTH default device AND default communication device (there's a difference and both can be selected).

I found the only way to resolve this issue was to delete the RealTek HD device in device manager then scan for hardware changes and re install.