This prompted by a sign seen in a local public library. Which do you say (and is this a UK/US difference)?

Question:
Library staff has been instructed to inspect packages if alarm sounds.
Library staff have been instructed to inspect packages if alarm sounds.

Choices:
staff has been instructed -- and I'm UK/Commonwealth
staff has been instructed -- and I'm US
staff have been instructed -- and I'm UK/Commonwealth
staff have been instructed -- and I'm US

 

I chose the first one because I'm Canadian, so I guess that's Commonwealth. M-W's Dictionary of English dictionary calls this notional agreement, and it is a UK/NA difference.

I always say faculty is or faculty members are, so I'd say staff the same way.

BTW, nice to see you again, goofy. Stop by more often!

I need an "other".

I use both about equally, as I do with other similar nouns such as team or government.

I usually say "staff have" but MS Word always tries to correct me to say "staff has".

Whis is correct?

In which library did you see the sign?

BOTH are correct. That's the point. It depends on whether you are considering the staff (team/band/orchestra/committee/etc) as a single entity or a collection of individuals.

To say one or the other is incorrect and should be corrected is prescriptive nonsense.