personal pronouns - Narrative in second person: singular or plural?

The lack of distinction of singular-plural pronouns for the second person in English (quite strange for native Spanish speakers, as myself) is usually unimportant, I guess, because the ambiguity is either irrelevant or obvious from them context. But I was wondering, from a translator point of view, about narratives in second person. Take for example the beginning of "The catcher in the rye":

If you really want to hear about it, the first thing you'll probably
want to know is where I was born, and what my lousy childhood was
like, and how my parents were occupied and all before they had me, and

all that David Copperfield kind of crap, but I don't feel like going
into it, if you want to know the truth.

Or, from "The mating season" (P. G. Wodehouse)

I wonder, by the way, if you recall this Augustus, on whose activities
I have had occasion to touch once or twice before now? Throw the mind
back. Goofy to the gills, face like a fish, horn-rimmed spectacles,

drank orange juice, collected newts, engaged to England's premier
pill, a girl called Madeline Bassett ... Ah, you've got him? Fine.

In Spanish, these examples areusually translated as plural (ustedes/vosotros), but the truth is that literature uses both forms: singular (the author speaks directly with the present individual reader) and plural (the author speaks globally to "the public").
Do English native speakers assume (from some rule, convention, or spontaneously) the singular or the plural person here, or it's inherently ambiguous?