I wanted to open a new project in a separate window in IntelliJ and I "accidentally" clicked "Remember this decision and don't ask again" and clicked "open in the same window"!
Since I have more than one project it is getting really annoying to switch! Where could I change this setting?
It can be changed in in File | Settings/Preferences | Appearance & Behavior | System Settings | Project Opening (or, before version 15, File | Settings/Preferences | General | Project Opening)