Hey there
An easy way could be using the trigger overlap event (which you’re using to switch music) to manually adjust the volume of your footsteps audio component, and the ambient sound.
Another more elaborate way is using an audio gameplay volume - add one to the scene, at the trigger’s location, and add a volume attenuation component to it. this will controll the loudness of sounds outside the volume when the listener enters, and vice versa, then you can tweak its parameters to your liking.
You may follow this tutorial:
Audio Gameplay Volumes Quick Start
Good luck !