English for Today by Ganiu Abisoye Bamgbose (Dr GAB)
TWO RULES IN ONE: INDEFINITE PRONOUNS
How is everything?
All ~are~ fine (nonstandard).
How is everything?
All is fine (standard).
How is everybody?
All ~is~ fine (nonstandard)
How is everybody?
All are fine (standard).
On the one hand, indefinite pronouns (everyone, everything, everybody, somebody, anybody) take singular verbs. On the other, the pronoun, all, attracts a singular verb when it is used to refer to things and it attracts the plural verb when it refers to persons.
GAB