One thing I've never understood (and hopefully some Casio geek can shine a light on): why do almost all old Casio models have a 24/12h time switch taking the premium spot as one of the main 4 buttons, instead of having it buried deep in the (awkward) menus. Seems to me that something like alarm or stopwatch setting or a second menu action button would have been far more useful.
Those buttons are the menu. The idea of menus on watches is a modern ux extravagance. I don’t have the satisfying answer as to why they dedicated a button to 12/24 hour time but my guess is that it’s simply a cool digital feature and stands out against the limitations of analog watches.
A few months without doing them, and it was hopeless trying to remember how to do them again.