I did as you say (I think) but it doesn't work. I have to save the files in external hdd, "nas"
-v /var/media/nas/film/config:/config \
-v /var/media/nas/film:/downloads \
-v /var/media/nas/Film/watch:/watch \
Your problem is that you don't know almost everything about docker. I understand that there are very bad manuals for users that define docker as "an open-source project that automates the deployment of software applications inside containers by providing an additional layer of abstraction and automation of OS-level virtualization on Linux" and this does not nothing helps.
I will try to define things in another way:
(1) Docker is an environment for executing other applications or systems called 'containers' with an iron control of access to system resources (hardware, networks, storage, ...)
(2) A 'container' is an executable package generated by docker when executing commands are applied to other packages called 'images'. This allows the user to customize the way the docker 'image' works and its interaction with the environment (hardware, networks, storage, ...)
(3) A docker 'image' is a package created by an application programmer to be used under 'docker'. If you are not a programmer you may never need to create a docker 'image'. Inside a docker 'image' there is nothing real, everything is virtual (directories, files, networks, ...).
Now I answer your question:
To modify the 'container' "9091-transmission" you need (1) stop the execution of this container (docker stop ...), (2) after you have to delete it (docker rm ...), (3) then it can be It is convenient to delete the 'images' that are not being used by any 'container' (docker rmi ...), and (4) finally execute the docker command to create a new 'container' with the command line modified to your taste. To get the full list of commands just type 'docker'.