Unsolved AERB Wireless 2.4GHZ keyboard - Change default "a" & "b" in game

[emdleb]

Dear Gamers,

I have purchased a 2.4GHZ wireless keyboard off Amazon (https://www.amazon.com/Aerb-Wireless-Keyboard-Touchpad-Rechargeable/dp/B01HG8DB5E/ref=sr_1_fkmr0_2?s=electronics&ie=UTF8&qid=1493578532&sr=1-2-fkmr0&keywords=aerb+keyboard+touch). It works great on Debian and Recalbox UI, however, when I configure the "controllers settings" in Main Menu, it doesn't take effect in game. When I start "Super Mario Bros 3" on NES, I am still forced to use "z" & "x" on my wireless keyboard instead of the buttons I configured in the Recalbox main menu (home="a" ; Volume down ="b"). I tried pressing the hotkey+B and Changing the complete libretro controller configuration following this link "http://recalbox-wiki-rtfd.readthedocs.io/en/4.0/EN/Custom-controller-mapping-for-specific-system-(EN)/" but I keep getting the same results.

Do you know how to change the default "A" & "B" in the game, to be similar to that of the emulationstation?

Setup:

Raspberry pi Zero W
Emulationstation V2.0.1A
Aerb 2.4GHz Mini Wireless Keyboard with Mouse Touchpad

[acris]

Recalbox doesn t use keyboard for game only gamepad.
Recalbox use snes mapping gamepad.
read manual : https://github.com/recalbox/recalbox-os/wiki/Manual-(EN)
keyboard is only in emulationstation.