Interestingly, at least to me, quite a few despised Americanisms are actually just more old fashioned English usage which result from the fact that the language did not (was not allowed to) develop in the early days of the colony.
I don’t think it’s that so much as that different words drifted in and out of usage. And not just from colonial times either – I was amazed when my wife used the word ‘galoshes’ and that’s a 30s Enid Blyton type word here.
There’s no standardised English anyway. So no-one can be wrong. English has always been evolving, and always differently in different geographical areas.
Plus, if you are just looking to be a snob towards Americans, why don’t you have a think about how many American words we’ve adopted?
Given how long ago they diverged it’s actually amazing how similar they still are.