Originally Posted by Mediocrefunkybeat
The usual method would be to find the 'normalise' function on the wave editor. It raises everything to 0db using the loudest part of the track as a reference; so it won't compress the signal. Assuming the highest peak on your recording is already below 0db, then it should raise the overall level on the waveform.
Excellent answer, I never had the need to this fonction but I will keep it in mind, thank's.