You cannot configure mIRC one way or the other. It depends on your OS language and/or language packs installed. The new version may change what you see because it's not Unicode. In general, Ctrl-I and Ctlr-U should be the only ones you won't see. There isn't any good way around that. Khaled is aware of it and has considered possible options for avoiding that problem, but there really isn't a good solution.
