Though it appears that way, the variables are never actually in clear text. The balenaCloud dashboard is secured via HTTPS, and the devices are not reachable, except through SSH or the balenaCloud dashboard, which tunnels to the device over a VPN. So, other than someone looking over your shoulder, that data should remain secured.
Audio out issues are common, and there are some diagnostic steps and settings that will affect audio output. Start here for troubleshooting , and also read through the audio device config info here  and here .
Let us know if those don’t solve your issue. Also, do a search through the forums on audio output problems, as that is a common topic for help.
One quick note is that if you have HDMI connected when the device boots up, the automatic sound output selection will (sometimes!) choose HDMI out instead of the 3.5mm jack. The links above explain how to manually select/force the output.