improve the sound quality

Hey @joanlee9494, welcome to the Sonos Community and thank you for your post!

Sonos gives you different options to adjust sound quality, depending on the kind of speakers you have and what device you use for the Sonos App.

You should always have the option to adjust EQ settings as described here.

If you have an iOS device (iPhone, iPad) you can also give Trueplay a shot.

Please bear in mind that sound and also sound quality can be a very personal experience, opinions on what sounds good differ and sometimes subtle changes in the speakers environment can make a audible difference. You can take speaker placement, area desired to be covered by speakers and surface textures into consideration.

Hope this helps!