Well, ChromeOS is super faulty. It blocks any hotkeys when you didn’t select the app, so unfortunately it won’t work for you.
You should try running the app in Administrator mode. Otherwise, try reinstalling the latest version and the correct installation.
Unfortunately, not in app. Here’s a tip on how to do this in OBS. First, mute the VeadoTube Mini window. Then, adjust the Mic bar to a loudness you think fits perfect.