Prosody config keeps reseting

Hello all,
I implemented changes in jitsi-meet.cfg.lua file to implement a prosody module. I then saved the container as an image and the changes were reset. I also tried saving the desired jitsi-meet.cfg.lua in the same root directory as the prosody Dockerfile and used:
COPY ./jitsi-meet.cfg.lua /config/conf.d/jitsi-meet.cfg.lua
It didnt work.
Next I tried to just implement a simple text file in /config, that also didnt work.
Can somebody please help and give information on why the /config directory can’t be changed and how to change it.

With regards,
Martin