An audio file can be perfectly valid yet too quiet or too loud compared with other tracks. Volume adjustment changes signal amplitude without requiring a full audio editor.
Adjust volume in Bethemesh
Use Audio volume adjuster, import the file and choose the desired level. Processing remains local. The main Audio guide connects this operation with conversion, trimming and merging.
Why can a large increase distort?
Digital audio has a maximum representable level. If gain pushes peaks beyond it, clipping can occur. Increase gradually and listen to the result; louder is not automatically better.
Reducing one loud track can also be better than boosting every other track. This matters before a merge; see merging audio files of different formats.