Output Volume to loud

I’m using Ardor 5 on Elementary OS.

As an input device I use a USB microphone: t.bone SC 420 USB.

When I connect headphones to the microphone’s headphone output, the volume is way too high.

My questions:
1.) Can I adjust the output volume somewhere?

2.) Can I use the headphone output of my laptop as the output? How?
For example, when I watch videos on YouTube, I can choose where the sound is output in the audio settings - regardless of the sound input.

Is there any way to do that with JACK?

The monitor controls are what you want to enable. That lets you control playback volume separately from recorded amplitude.
Ardour manual monitor section

Yes, but it is probably more complex than you want to get into for now. You can look up the jackd wiki information on using multiple cards. I think the latest version of Ardour has a way to do that using the ALSA backend, but that capability built in to ardour is somewhat new, I have not used it myself so I am not sure how that is setup. With jackd depending on which version you are using you either have to load the internal client for resample (jackd v1) or start and external program, zita_j2a recommended, and then route your output to that zita_j2a output (jackd v2).

Thanks, perfekt! That ś it.

Nevertheless, I will come back to my question:
How can I use the headphone output of the laptop with Ardor?
I ask because the headphone output of the USB mic is incredibly noisy. In addition, I don’t always have to have the microphone connected to mix.

Assuming you use Ardour 6, yes you can. In Menu > Window > Audio/MIDI Setup use

Audio-System: ALSA

Then select your USB mic as Input-device and your onboard soundcard as Output-device.