I’ve recently been working on a song but have just realised some tracks weren’t recorded hot enough -20db. where is the gain pot located? is manually raising the bar on the wave form the same thing too? 
Clip gain
Push E and change Pre Gain in Channel editor
Show the Pre rack in the extended Mixconsole
Take your pick.
I often raise the gain by using the bar on the waveform.
But when I need that much gain (20db) another technique is using the maximizer plugin. I even apply it destructively to the file sometimes by highlighting the file and using the audio menu.
The benefit of doing it this way (destructively) is that it gives you reasonable levels on the file permanently and also gives you the opportunity to clip off some unnecessary peaks at the same time.