voiceover voices switch on audible.com on m1 mac running big sir, help

Hi,
I got a mac mini for Christmas, and love it, and I've actually had the issue I'm about to describe since then, but I can't find a solution anywhere else. Ok, so this is what happens, I go to audible.com, and voiceover uses Tom, which is my default voice, but when I browse books by heading, it autoswitches to the Alex voice, which compared to Tom seems to be really quiet through the mac mini speakers, although it's the same volume. Plus, it's just really annoying, not to mention weird having my voices switch without warning. How can I STOP this and have audible.com be read by my default voice, whether it be Tom, siri, or whomever? My voiceover activities are turned off, there are none in there, so safari isn't using a different voice. The only site I've found that exhibits this behavior is audible, I just want voice continuity! :)
Thanks