This help page explains how to do that:

http://www.e-junkie.com/ej/trouble.affiliates.history.htm

I asked one of our Developers to take a look at this, and it might turn out to be fairly simple to add a month selector to the masspay file download screen; if so, that enhancement could be ready quite soon. We're still looking into it at the moment and will followup here if we've got good news to share. :^)

I've asked Development whatever happened to this request; it seemed they were making some progress on it last year, but perhaps it fell by the wayside due to more pressing duties. Since the screen that generates masspay files is an HTML page that's not built-into our current Flash-based Admin panel, in theory it should be fairly straightforward to modify, though I can't say what back-end obstacles they may have encountered unrelated to the matter of modifying the screen itself.



Most other major feature/functionality improvements are "backed up behind the dam" of a new HTML-based Admin panel that we can actually modify to add new settings/controls to manage those features, and we've been making steady progress on that project since last spring, after some false starts and unexpected setbacks in 2011.