You likely have to select the desired hairpin from the SmartShape Panel on the right of the screen

http://usermanuals.finalemusic.com/FinaleWin/Content/Finale/Smart_Shape_Palette.htm?Highlight=crescendo%20metatool 

or use the appropriate MetaTool for the SmartShape you want.

http://usermanuals.finalemusic.com/FinaleWin/Content/Finale/ht-metatools.htm?Highlight=crescendo%20metatool 

(You'll have to scroll down a bit to find the SmartShape table on this page.)