how do you use the laptop's speakers only when connected to a computer monitor?

[Paul2]

so, i hooked up my laptop to a computer monitor for much bigger screen and 1080p resolution.  I been hooking it up like that for over 2 years.  lately, this past few months, i notice my laptop's speakers sound much better than the pc monitor's built in speakers.

i tried to set the laptop's speakers as the default speakers but it doesn't seem to set on the Hardware and Sound setting.  the sound still only come out from the pc monitor's speakers.  So, is it even possible to disable the computer's monitor speakers and enable the laptop's speakers?  The laptop is hooked up to the pc monitor via HDMI.

[Paul2]

yesterday afternoon, i finally able to switch to laptop's speakers for sound instead of the pc monitor's speakers.

i guess either because i did a dell recovery on my laptop recently or maybe i reinstalled pc monitor model status by disc instead from auto detect update from the web that i finally able to switch the sound to come from laptop instead of the pc monitor.

but the strange thing is i think my laptop got some kind of nasty viruses that even after i did a dell recovery, the cpu still eats a lot of performances and powers whenever i play some adobe flash media on the net and that media is only like 360p resolution.

i remember days ago, i detect a svchost.exe (netsvcs) that eat up cpu performances and i am suspicious this svchost.exe (netsvcs) is some sort of virus or malware...