Recently, I used Kdenlive to edit my videos. It worked for me.
I needed to install a library file called "libsdl1.2debian-pulseaudio" for it to handle the sound. I needed to restart the computer as well before I could use it.
See the following information I got:
I learned the basic things here:
An Intro to Video Editing with Kdenlive Part 2: Creating your First Video - YouTube
I learned how to enable the sound here:
Ubuntu sound has gone on KDEnlive | Kdenlive