One of the unforseen consequences of evolution is the loss of the ability to grasp the handle of an open door and pull or push it closed.
Anthropologists believe this is a direct consequence of the installation of automatic sliding doors and apartment doors with lever sprung closures.
In short, people have become used to doors closing themselves and would rather disturb their neighbours by allowing their doors to slam shut than, in grasping the door handle, waste a precious nanosecond that could otherwise be used Facebooking their imaginary friends.
Similarly, doors that have no automatic closure are left open because logic dictates that if they needed to be closed, they would have a spring closure attached.
But seriously, put a polite note on the door asking people to close it after them. That’s all you need to say: “Please ensure this door is closed after use”.
If that doesn’t work, get your committee to send out a note to ALL owners telling them the screen doors are there for a reason.
If neither of those work, and you are sure it’s the new neighbours, ask them if they have any idea who it is that keeps leaving the door open.
Finally, before you get the strata committee to invest in spring closures, the accepted wording of a personal approach is “Mate? The screen door? Really?”