bbPress.org

no simple way to do this in your functions file, the bbpress widgets are pretty unforgiving in allowing you to tinker with them.

two immediate choices – fork the widgets code into your functions file and rename it – requires some php and WordPress knowledge or
Just amend it in the bbpress file – AND make a note to need to change it on bbpress upgrades.

The latter upsets the purists, but it’s only codes and you can’t be arrested for changing code !