I have fixed 3drefit to correctly implement the '-substatpar' option, which did not work when we were in Guangzhou. This fixed code has not yet been compiled into new AFNI binaries, though. I'm working on some other fixes that were suggested while we were in China.
The method to change the sub-brick in question would be something like
3drefit -substatpar 0 fizt -sublabel 0 Correlation DATASETNAME
where '0' is the sub-brick index. I will post here on the message board when new AFNI binaries are ready -- probably Friday (of course, that will be Saturday in China
)