Ascending posts within month

Hi. I want to add my appreciation for this neat little plugin. I do hope it will go on being supported.
I had a problem a year ago which got no replies – then I was ill. Could somebody please advise me what and where to put a line in my php file to do the following.

I want my posts to follow the usual convention, with the most recent on top, but my archives to be chronologically ascending. The archives are successfully chronological ascending by year and month, but the posts within a month are still descending. Can these be reversed too?