Mold is the American spelling for all senses of the word meaning, among other things, (1) a frame for shaping something, (2) to shape in a mold, and (3) any of various fungi that commonly grow on organic matter and are often associated with decay.
Mould is the British spelling, American English has no mould, and British English has no mold.
Australian and Canadian English favor the British spelling, though mold is fairly common in Canadian publications.
WE prefer the spelling MOULD, as can be seen in the logo of our event and in all communication.
It’s a preference not a right or wrong. We prefer the British spelling just because United Kingdom is part of the European continent, just like us. ;)