@zing You´re a genious!! I edit (previous backup) the es_input.cfg in \SHARE\system.emulationstation folder, change the default value of A for B value and also changed the Hotkey value for the default one, rebooted and voilá!! I have now set my buttons like i have in my old recalbox 4.0 and all of them work perfectly.
This is the config that worked for me, in case someone has the same issue:
<inputConfig type="joystick" deviceName="GPIO Controller 1" deviceGUID="15000000010000000100000000010000" deviceNbAxes="2" deviceNbHats="0" deviceNbButtons="9">
<input name="left" type="axis" id="0" value="-1" code="0" />
<input name="down" type="axis" id="1" value="1" code="1" />
<input name="right" type="axis" id="0" value="1" code="0" />
<input name="up" type="axis" id="1" value="-1" code="1" />
<input name="r1" type="button" id="5" value="1" code="311" />
<input name="l1" type="button" id="4" value="1" code="310" />
<input name="y" type="button" id="3" value="1" code="308" />
<input name="x" type="button" id="2" value="1" code="307" />
<input name="b" type="button" id="0" value="1" code="304" />
<input name="a" type="button" id="1" value="1" code="305" />
<input name="hotkey" type="button" id="8" value="1" code="316" />
<input name="select" type="button" id="6" value="1" code="314" />
<input name="start" type="button" id="7" value="1" code="315" />
</inputConfig>
<inputConfig type="joystick" deviceName="GPIO Controller 2" deviceGUID="15000000010000000200000000010000" deviceNbAxes="2" deviceNbHats="0" deviceNbButtons="9">
<input name="left" type="axis" id="0" value="-1" code="0" />
<input name="down" type="axis" id="1" value="1" code="1" />
<input name="right" type="axis" id="0" value="1" code="0" />
<input name="up" type="axis" id="1" value="-1" code="1" />
<input name="r1" type="button" id="5" value="1" code="311" />
<input name="l1" type="button" id="4" value="1" code="310" />
<input name="y" type="button" id="3" value="1" code="308" />
<input name="x" type="button" id="2" value="1" code="307" />
<input name="b" type="button" id="0" value="1" code="304" />
<input name="a" type="button" id="1" value="1" code="305" />
<input name="hotkey" type="button" id="8" value="1" code="316" />
<input name="select" type="button" id="6" value="1" code="314" />
<input name="start" type="button" id="7" value="1" code="315" />
</inputConfig>
Thank you so much for your patience, your time and your kind help. Hope that in next release the splash screen sound will be fixes.
King regards