distorted sound after export

Hi, i'm having trouble with my premire pro file as i've had to amplify it since the wave forms in (adobe audition) are not loud enough, whilst everything is fine in premire pro as soon as i export it; the audio file (since im saving it as an mp3) sounds very distord and muffled. None of the youtube clips or google searchers are helping.

Ideally id like to fix in premire pro

kind regards elise