Newbie - trying to get control Y axis of FPC using keyboard

I know this has been asked multiple times, but I still have not been able to figure out how to control the Y parameter (UP/DOWN) of the FPC using keyboard commands. I want the X and Z functions to remain the same, but want to be able to move the FPC up or down using “U” for “up” and “D” for “down” - I know, this is probably a painfully simple-minded question - but any help would be greatly appreciated! I have tried flight and hover scripts I have found online - but none seem to be as simple as the sort of straightforward “up/down” I am looking for - help!

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