Szerintem ebben a file-ban nezelodj: /usr/share/jitsi-meet/lang/main.json :)
Hint:
docker exec docker-jitsi-meet-stable-6865_web_1 grep -r '"Secure and high quality' /usr/share/
/usr/share/jitsi-meet/lang/main.json: "headerSubtitle": "Secure and high quality meetings",