change of button of keyboard is not possible on setting of MCPE Android

the keyboard is working until playing , but it's not possible to change/edit button of keyboard on setting
please find us a solution
the game will be amazing with keyboard, and please don't forget to unable using of mouse on the game
and thanks
i hope that will work on futur version
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device : Tablet carrefour CT820 ( this problem is on all device android ..)
OTG is working on my tablet..