Apply Normalize Region/Cell Gain Again ⌃G
I habitually change Region gain on tracks that I mix. My current target is peaks of -12 dB. I don’t change region gain if all of the tracks come from a “live” performance where players are typically self-adjusting. In those cases I work with the faders all set to about -9 dB to start.
You can normalize the gain of selected regions in the Tracks area, without opening the regions in the Audio Track Editor. The Normalize Region Gain menu command is non-destructive: the original file isn’t altered, so you can return it to its original state.