I didn't quite manage to fix the issue, but at least to overcome it. Let me explain: originally, I downloaded the Recalbox OS v4.1.0 from https://github.com/recalbox/recalbox-os/releases/tag/4.1.0 This version has the issue with not being able to save the settings. This version is installed by simply copying a bunch of files to the SD card and letting the RPi boot.
But then, I discovered the version 17.12.02 of Recalbox, that I downloaded from https://archive.recalbox.com This is an image (img.xz) file, that I installed using the Etcher software (as mentioned on the download page) on the SD card. This version of Recalbox seems to do the trick and I was able to enter several settings that were still set after rebooting the RPi.
I hope, this helps everyone with the same problem.
Ihad the same problem. As @LBR59 said, the video is located here:
If you are on Linux (but I can imagine ffmpeg tools are also available on windows), this simple command line will create "outputfile.mp4" with the sound lowered:
ffmpeg -i recalboxintro.mp4 -vcodec copy -strict -2 -af "volume=-15dB" outputfile.mp4
Hope it may help
this is a Recalbox OS 4.1 download. The only thing I have added are roms to the emulators that do display. Once it is booted it only displays 7 emulators, but if I open up the recalbox share folder, it shows that it has almost every emulator. I will read into the files more though, thank you.