Hi @AurelDisanto,
I believe the setting you're looking for is this one from the RStudio Server Pro admin guide:
In accordance with the Base Directory Specification, the environment variables
specify the location of the rstudio folder. For example, to store system-wide
preference configuration in /var/config/rstudio/rstudio-prefs.json, you would
set the XDG_CONFIG_DIRS variable to the value /var/config.