I recently had a similar situation and was surprised that I couldn't change multiple label texts in the properties. The difference being that my labels all had the same text to begin with but obviously that wouldn't have helped. So in your case, labels having different text, you would have to select all labels individually. Well if I have to click on each label to select it then I figured I might as well place one label with the correct text, inherit it's properties and then ctrl+alt click the others. No more time consuming than selecting them all in the first place, Just requires holding down one more key. Just need to make sure that "Label text content" is checked in the "Element transfer settings"
Strangely enough though, you can select a dimension strand, multiple dimension strands and/or several texts of dimension strands, double click the text tool and change the text of all of them in one foul swoop. It would be nice if we could do that with both the label tool and the text tool. I hope that if I'm missing something that someone sets me straight.