I'm not a native English speaker, but couldn't one "affect change" as in "simulate change"?
I don't think so. It doesn't make sense. You could affect a
change in accent, or a
change in style, but you can't just affect change. You might say ''affect a change'' if the thing changed has been previously identified. Such as, ''he spoke with a common accent, but when he went to university he affected a change.
I think we have exhaused the possibilities here. In any case, Obama has neither affected nor effected changes.