bb2007 may or may not have that feature in it, I don't recall.  Way to find out is to RightClick at the bar and see if you can select "Bar Settings" and if you can, whether or not the Bar Settings window that pops up has an entry for Number of Beats in the bar.  Before the advent of that feature, we used to invoke a Style Change to get the 4/4 and 3/4.  There is a workaround on that if you want the song to start in 3/4 and then go to 4/4, see the pgmusic FAQs for bb2007 for more info, but it involves starting with a blank measure of 4/4 first in order to get it to work.  If you start with a 4/4 measure, all works okay. 


--Mac