...if you're viewing videos using Flash Player, then you'll need to download special software or use specific scripting to do it on the machine. (For example, do a Google search for "Flash Player equalizer".)

Other than that, most media players have their own equalizer settings panel.

Preferably though, I chose to purchase a set of speakers, including a small subwoofer, which allows the user to set basic high and low frequency using the speaker's control knobs.

It's your choice.

Hope this helps.