Jitsi Docker - Change default FPS for screen sharing or video format


I am trying to set up a jitsi instance on my private server, so that can provide video chats for the elementary school of my daughter.
Therefore I have setup the jitsi docker images behind a nginx reverse proxy, and everything works smoothly.

But to be able to use, I would like to define
a.) The default resolution (and bit rates and video codec, if possible)
b.) The FPS value of shared screens

Do I have to edit some buried-deeply config files, or is it possible to change the behaviour in the exposed config files. If yes, please tell me which file to edit…

Best regards, and thanks for this great work,