Q about QM spookiness

[Mudhammam]

When physicists talk about the spooky behavior of particles-waves, such as in the famous double-split experiment, are they only referring to the actions of individual particles? Or do those results also apply to particles that have 'clustered' with others, for lack of a better term (okay perhaps I need some help on that too--is it, again simply put, positive and negative charges, with gravitational and conservation laws, that caused atomic arrangements to emerge and so on and so forth until there are macroscopic objects?).

Thanks and sorry in advance for the naivety.