Some help on button remapping required!

[tinybilbo]

I've installed retropie 4.4(rpi3), setup a bunch of console and arcade emulators successfully.
I've changed the theme and scraped all relevant artwork and metadata.
It all runs and looks lovely...

But... I'm struggling with mapping controls for the individual emulators.

I have a PiCade which uses a Joystick & 10 buttons mapped as keyboard controls (via a PiHat)
The button (keyboard) controls are as follows

A=x
B=z
X=shift
Y=space
RS=ctrl
LS=alt
LT=escape
RT=enter
START=i
SELECT=o

I'm working with the Atari2600 (lr-stella2014) to start with...
What file do I need to edit? and what would I put in that file in order to map (to name just a few)...
Joystick button to A (keyboard=x)
Select to SELECT (keyboard=o) (Do I need to remap this?)
Reset to START (keyboard=i)
L.Diff A to Y (keyboard=space)
L.Diff B X (keyboard=shift)

Thanks

[mitu]

@tinybilbo Take a look at https://retropie.org.uk/docs/RetroArch-Configuration/#example-default-per-system-retroarchcfg. You'll need to edit the /opt/retropie/configs/atari2600/retroarch.cfg file (also available via file shares at \\retropie\configs\atari2600\retroarch.cfg) and change the mappings for input_player1_<button_name>.

The defaults are

input_player1_a = "x"
input_player1_b = "z"
input_player1_y = "a"
input_player1_x = "s"
input_player1_start = "enter"
input_player1_select = "rshift"
input_player1_l = "q"
input_player1_r = "w"
input_player1_left = "left"
input_player1_right = "right"
input_player1_up = "up"
input_player1_down = "down"