Changing text on entire slide show

[greenda]

Is there a "one stop" way I can change text color/size on all the slides at once?

[Corfy]

If you have all the text set up using the same style, then all you have to do is change the style (F11, right-click on the style and select modify), and all the text will follow.

If you don't have all the text set up as a style, or you did a lot of customizing of the text format, then this probably won't work. But that is the strength of styles.

[parmruss]

You can also try going into outline view, selecting all and changing the font formatting there.