A quick keyboard shortcut for changing the case of selected text in Word:

Shift+F3.

Depending on the case of the words you want to change, and what case you want to change them too, you may have to press Shift+F3 a couple of times in succession to get the case you want.

via Word: Change case « CyberText Newsletter.

Gar nicht gewusst. Hätte diesen Tipp schon früher gebrauchen können.