Hi,
Thanks for including the file.
Because the file already contained a tempo change to 60, only the region that was initially 120 was entered in the Tempo "Region" following my first instructions. I forgot about that safeguard for an existing tempo change
Fortunately, when using the Tempo dialog, you can either (1) select the Region beforehand or (2) enter the last (or some huge) measure number for the ending of the region after the dialog is open, and Composer correctly assigns the new tempo to the entire song.
Alternatively, you can use the Graph Over Notes tab, click on the Tempo button there, and just choose the "Enter numeric" button on the palette tool bar (the "96" button). The full song was correctly selected there in that region, so all you have to do is click "Ok" to save the change to the entire song.
Enjoy
Sherry