Cannot move recording volume slider

I have recently installed Audacity 2.2.1 from the standard repository on Linux Ubuntu 18.04.

I followed the official Tutorial (I’m new ), and wanted to make a test recording because I suspected the microphone should be boosted.

When I click on Start Monitoring (for the recording levels) it peaks around -20. Unfortunately the recording volume slider is stuck at max, but I suspect it is just deactivated (I can not move it), and it seems no boost is applied at all.

I have clicked through the settings a couple times already: Is there anywhere I have to enable the user to tweak recording / playback levels? Btw. I can move the latter.

Any other suggestions?

That’s correct. For most Linux distributions (including all official releases of 'buntu), recording level adjustment is not available to Audacity. Use the system sound controls instead.
I’m not sure exactly where those settings are in Ubuntu, but in Xubuntu there is a loudspeaker icon for accessing “Sound Settings”.

thank you