Total beginner here. I was working on my first map when almost all of my world geometry outlines turned green in the 2d viewport. I think I accidentally hit Ctrl-t with multiple things selected and made them into some kind of group thing? Whenever I click on one of the green objects it selects all of them. I've tried switching the top right between Group and Object and it still selects all when I click one. I'm sure it must be a simple solution but I can't figure out what it is and right now it's quite difficult to edit stuff when it always selects so many objects.