From block producing node to snark worker node

[canutodev]

Let me start by saying that I activated a mine node for producing blocks just two days ago and it seems to be working well...
Today I updated the client to version 1.4.1. I have set up a second node but I would like to use it as Snark-workers, node2 is an exact copy (apart from hostname and IP) of node1 so at the moment it also works in the same way as the first. I took a look at the official documentation to activate the node as Sanrk-workers but I don't understand how to change from block producer to Snark-workers. The client starts as a service at boot, in the documentation there are these steps:

To start a SNARK-worker, run these commands:

mine client set-snark-work-fee <FEE> mina client set-snark-worker --address $MINA_PUBLIC_KEY

do I have to stop the client before issuing the above commands?

If your daemon is already running, restart the daemon with these flags:
args={["-run-snark-worker $MINA_PUBLIC_KEY", "-snark-worker-fee <fee>"]}

since the node starts as a service, where should I insert the args=.... line?

Thanks to anyone who wants to dedicate a few minutes of their time to me.