I never tried it but I think you have to create them in the .jitsi-meet-cfg/web folder and it will automatically work since the config folder is already mounted to the container.
I did try but unfortunately did not work. I feel it takes config.js and interface_config.js from online and not from my .jitsi-meet-cfg\web folder. Either that or docker image overrides the settings.
How exactly do your custom files look? I wasn’t able to test it before but I tested it today and the custom-interface_config.js file has to look like this for example:
Yes I made it to work There was a problem with my docker somehow. I re-installed and re-cloned jitsi again and then altering custom-interface_config.js file worked
Weird since I do not know why it did not happen at first place.