Right-click → Mixing & Effects → Volume Knob.

Volume Knob
Gain -6.0 dB
Input
Output
In 1
Out 1
-6.0 dB

A knob carries up to 8 lanes. Each lane is its own path - In 1 comes out on Out 1 only - so a stereo pair takes two lanes and stays stereo. A new lane appears when you connect to the free one.

DoHow
Set the levelDrag or scroll the knob (Shift for fine steps): -60 to +12 dB
Reset to 0 dBDouble-click the knob
MuteMUTE
Mute or unmute every laneMute all paths / Unmute all paths

The one level applies to all lanes. For separate levels, use separate knobs or wire gain.