[lr-scummvm] map joystick buttons to keys and mouse buttons

[orclex]

Hello,

I have a retroflag GPi Case 2W and I'm using lr-scummvm on retropie.
The controller buttons are accessed via the Xbox driver.
Currently, lr-scummvm uses the left and right shoulder buttons as left and right mouse buttons, which is very inconvenient. I would like scummvm to use the B/A buttons of the controller as mouse buttons. How can I do this?

I have tried to change the keys in the scummvm options of a game. This works, but even if I save the configuration, the next time I start lr-scummvm the configuration is reset.
Also, the scummvm menu doesn't use the changed keys and I still have to use the shoulder keys there, which is confusing.

Can I set a scummvm-wide default for joystick buttons somewhere in a scummvm.ini or retroarch.cfg to emulate a left and right mouse button?
Does anyone have an example?

Thanks a lot!