Are you saying that you made a change to the settings.js file, and the service did not restart? If so, then that is to be expected. There is no "watchdog" built-in to node-red... you would have to either create a flow that watches the userdir, or run it under nodemon -- or just do a manual restart.
Didn't we cover this a few days ago. I gave the information on how to start node-red using the Windows Scheduler. NSSM can be used but isn't necessary. The Scheduler will try to restart a failing task but you may find something like PM2 to be more reliable and controllable (at the cost of significant additional resource use).
which settings file did you edit... - when we start the first time the default one gets copied to the users directory. If you edited the "old" default one - then it won't affect the user one that is being used..
Actually the default userdir should be in C:\Users\xxxxx\.node-red
If you can show us the console logs created when the service starts, that would make it clear. But I believe your Startup directory in the Nssm config is wrong -- it should be the userdir that I listed above.
The path you are showing is not correct... typically there is a hidden directory called .node-red underneath your user directory, not another directory with the extension ".node-red".