People ask me which word is correct: canceled or cancelled, gray or grey, traveled or travelled, color or colour, theater or theatre?
Whichever variant you see listed first in the dictionary is the preferred spelling. It’s not a question of right or wrong, it’s just the preferred form. I find it interesting that in America we rarely use the “—our“ form of a word, but we do write glamour. Perhaps we think it looks more glamorous (which we do not spell glamourous!).
I am taking a break for a couple of weeks, so I’ll be back to torture you the beginning of August.