Upon vs. Apon

I can never remember how to spell this word. I'm always getting dinged by spell checker. Turns out the correct spelling is "upon." Let's see if I remember this tomorrow. It turns out that in Middle English the spelling was "apon," which may be where the confusion started in my childhood. I actually think we should write apon, otherwise we should change the spelling of a million other words for consistency. Like, we write "a lot" rather than "u lot." Or "agressive" rather than "ugressive." Or "anonymous" rather than "unonymous." Or "attractive" rather than "uttractive." Or "anderstanding" rather than "understanding."