Thank you. I actually found a way to do this though in a different way. However, the AUX method I am unable to replicate although I know I have done it accidentally before. I tried plugging it in improperly, but as soon as the contacts touched the plug, the computer already routed audio signals over AUX instead of Speaker...
Anyway, I have the Realtek Speaker/audio driver system thing. It has the Stereo Mix (in the recording devices section). What I ended up doing was to Use the Mixer, which makes a copy of all the sounds my computer is making, and send it through a different output. In my case, I sent it to my display through HDMI. (AUX doesn't count as a "different output", so plugging in a AUX will deactivate the built-in Speakers). Then at the back of my display, I connected my AUX external speaker.'
The above sounds complex, here is clarified version of what is happenning:
-Sound is playing through built-in speakers
-Stereo Mix from Realtek copies the audio signal and forwards it by HDMI to my display
-Display forwards the audio signal to the AUX external speakers.
This is the only way I found to reliably do it, however, there is a slight lag by about a fraction (half maybe?) of a second. So the external speakers are a bit delayed compared to the built-in speakers.