Hi mates, when I start NR it shows me:
Your flow credentials file is encrypted using a system-generated key.
If the system-generated key is lost for any reason, your credentials
file will not be recoverable, you will have to delete it and re-enter
your credentials.
You should set your own key using the 'credentialSecret' option in
your settings file. Node-RED will then re-encrypt your credentials
file using your chosen key the next time you deploy a change.
I've neve set credentialSecret and I don't want to do it, my system is safe and not exposed to anyone else, I don't want to encript nothing and avoid any kind of problem cloning/importing to a new system my flow, I don't want to risk to loose the ton of hours I've spent on NR building my flow, I just want to sleep fine at night 
Actually my flow is not encripted, I can open it with an editor and see all data, so I don't know why NR tells me it's encrypted with a system key it generated, can you please clear me more about that?
Should I leave it as now? (still in defaut as installed, about that setting).
Thank you