How to change the XRAY_MOUNT_ROOT once I’ve installed Xray in Docker?

Since the Xray containers are bounded to the mount points, you will not be able change them without reinstalling the containers.
To make this work you have to kill and remove all Xray Docker containers. This can be done with the following commands: 
$ docker stop $(docker ps -a -q)
$ docker rm $(docker ps -a -q)
After performing that, edit 'xray-env.conf' which is located under '$XRAY_HOME/.jfrog/xray/xray-installer' and then run ./xray upgrade and then ./xray start - which installs the new Docker containers with the new settings.