How to set autofire in mame 0.266

As far as I know, this is how I did it.

I go to plugin and I set autofire button. Basically I set a button that will autofire something when pressed.

I go to input for this game and eliminate that button.

Say button x in my game pad correspond to punch. I set button x in my game pad to punch. After that I remove x from normal punch button.

Works in final fight. Don’t work in double dragon. Work in double dragon but after I set all 4 buttons to autofire it doesn’t work.

I think it’s very awkward.

I wonder if I do it right?

Also once I add autofire button, how do I remove them?

Also where is the settings of this autofire located?