Do you have a presentation that contains text that needs to be spell-checked in more than one language? Or do you and your client or colleague work with different localized versions of Microsoft PowerPoint? It may be that you use English (US) and color is a perfectly valid spelling — but someone else in another part of the world uses English (UK) and their spell checker suggest that the word color be changed to colour. Or if they use the French version of PowerPoint, then both spellings of color/colour would be flagged as incorrect — they use the term couleur. You first need to have the proofing tools installed for all or any of the languages that you need to work within PowerPoint.