Make up your fookin' mind

[tangaroa]

I'm copying text from Notepad++ to a textbox in Palemoon (a firefox derivative). NPP has the word "Fulfills" underlined in red as a misspelling, but accepts "Fulfils". Palemoon accepts "Fulfills" but has "Fulfils" underlined in red. I assume that one of them is set to American English and the other is set to English.