How to manage startup applications in Debian?

So I'd like to manage my autostart applications and e.g. disable those which I prefer not to autostart. How can I do that in Debian 9.0? I could not do so via the System Monitor and I'd prefer a GUI over the console. In KDE's System Settings most of the autostarting software is not shown under Autostart (issue here ). Furthermore it would be nice if such a tool also displayed some information about the apps/processes such as what they do, whether they're safe to disable and e.g. things like whether many have them running as well and whether (many/specific) users have flagged them for being undesired.