Free Video Editor is said to be a lossless simple editor.
VidCutter x64 is another. Not sure where you can find it.
I don't know if you can alter volume with them.
BSFAG supposedly can adjust volumes, but I think it involves a re-encode.
Welcome to my BS Programs website! This is my repository of small programs I wrote for fun and become handy. They are also my playground on enhancing my programming skill. I put them here to share to everyone for free. Hopefully you'd find them useful, too. If you need help to build applications
It requires mp3gain and FFMPEG.
I've never used any of the above.
You can open a lot of video files in Audacity and then adjust the volume of the audio track. Not sure if that meets your requirements.