Hello there JimForster,
We see you're trying to turn up the input volume on your Blue Yeti microphone. Let's take a closer look as we do our best to provide some additional insight.
To get started, do any other audio input sources like the built-in mic or regular headphones with an audio input do the same thing? You can also try testing your mic with a different computer as well. These quick tests can be helpful in ensuring there isn't just an issue with your mic.
In the meantime, have you also checked the audio input volume in the System Preferences? If not, go to the System Preferences > Sound > Input section. Here, make sure the "Input volume" slider is turned all the way up.
Change the sound input settings on Mac
If you're using third-party apps or software for your recordings, try testing with a built-in Apple app like Voice Memos. Any change in the recorded volume?
If not, and if other audio inputs work just fine, you may also need to check with their support at: Yeti Support
We hope this helps!
Take care.