I am using PowerPoint 2013, and have charts with data labels. Unfortunately our conference room PCs were not updated yet, they have 2007. When we open a presentation in 2007, sometimes the data label changes from a number to [Variable] or similar to that. We've begun saving presentations in ppt, instead of pptx. This fixes the issue, but we loose the ability to edit the charts easily, we have to convert to edit. These presentations are for our president, we can't risk him going somewhere and what looked good on our desktop messing up when he presents. Is there a setting we need to change or something else we should be doing?