As a rule, Narator ducks the audio of your computer (sometimes even if you turn narator off it keeps the volume turned down!) so fixing your latter issue may fix your former. I'm not sure if you're sighted or blind, but if sighted this link provides two ways to disable Narator at start up. It should be relatively easy to follow if you're using a screen reader, but if you need me to rewrite it from a reader perspective let me know.
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It's also worth checking sound settings, as with audio conferencing platforms, Skype and the like, it will also audio duck if not disabled.