Audio Enhancement for 5 MP4 Videos

I need someone to increase the volume of audio on 5 of my MP4 videos. Each video ranges from 1 to 5 minutes in length. The enhanced videos will be used for a professional presentation, so it's crucial that the audio is sufficiently loud to be heard clearly in such a setting.

Ideal skills for this job include:
- Video editing
- Audio engineering
- Sound design

Please provide a sample of your previous work if available.