Since some people complains about the BGM and button's sfx loudness, I decided to update it with a new patch, with the volume reduced -3dB.
This issue is actually caused by the player's side speaker spec so it's hard to adjust it from my side.
Please let me know if it should be more quiet or loud later, so that I can adjust it better.
For people who prefer the previous BGM loudness, please change it through config>sound setting>BGM volume> change 2 to 3