Sorry for the troubles. Let's see if we can get you sorted.
The Mod Launcher is a One-Click Application, and I cannot control where it gets installed. It is a bit annoying. You can download the 7d2dmodlauncher.exe and place it where ever you like, and run it from there. You can add that exe to your Steam as a non-Steam game to get your overlays.
By default, the mod launcher will install in C:\7D2D\. This can be changed, as you found, by changing the Destination folder. It should save that setting. However, it appears it doesn't save or remember for you.
What kind of anti-virus software do you use? I've seen it do strange things to the mod launcher.
The Mod Launcher installs mods for 7 Days to Die, and not just for Starvation, so certain requirements need to be met for all the mods to play well together, even if you only play one.