Would this be the same for street fighter games then?
Older CPS1 games Street Fighter II, SF2 Champion Edition, SF2 Turbo/Hyper Fighting, etc) were dipswitch driven. After setting the difficulty you need to restart the game via the TAB menu, or exit MAME and restart it.
CPS2 games (Street Fighter Alpha and up) had the F2 test menu. After setting the difficulty, exiting the test menu via the menu's own command reset the game and applied the new difficulty.
And I do hope you're using this information to make the games harder. They are already far too easy.
