Know your audience! Which of the Englishes does it speak?

Use American spelling for American audiences.  

britishcouncilfoundation.id/en/english/articles/british-and-american-english 

Use American terms when writing on technical subjects for American audiences.

"... mathematics is singular. Math is a clipping, like 'lab' instead of laboratory, while 'maths' is a contraction, like 'attn'. " 

-- SOPHIE MCBAIN writing in an April 2018 piece in the News Statesman

Differences in prepositions "on/at the weekend" (usage ngram)

Differences in spelling between Canadian and U.S. Englishes: TBD   

from 
https://en.wikipedia.org/
wiki/World_Englishes

 If you use a Britishism, at best, your audience will view your   writing as having a slightly foreign flavor. At worst, your           audience will think your command of English is poor. 

  Is that the effect that you are aiming for? 

https://www.lexico.com/grammar/british-and-american-terms 

https://www.vogue.com/article/britishism-dictionary-translating-american-british-english

Found this! Map of popular last names by country.

All is not lost! Words take two-way trips across the Atlantic ocean. Some words from the UK are becoming more and more widespread in the Americas.

https://www.cambridge.org/elt/blog/2017/07/03/americanisms-in-british-english/

https://www.huffpost.com/entry/britishisms-in-american-english_n_5b69a9ede4b0b15abaa73cff

https://www.languagesoftheworld.info/sociolinguistics/americanisms-vs-britishisms.html

Discussions:

See comments https://davefarmer.co.uk/2012/05/26/americanisms-v-britishisms/

and here https://lithub.com/38-americanisms-the-british-cant-bloody-stand/