[...]how to change sound equalizer [...]
Hi!
This is hardware related, there is nothing to change.
You need a 5.1 or higher hardware for this to show on the default PulseAudio interface.
The other approach, is to install a SOFTWARE MIXER.
Do a search on Google, there are many choices available:
Linux multichannel mixerHope this will shed some light on the subject.
Good luck!