Keynote 
Set a default text box for a presentation
You can set your own font, color fill, and other elements for a text box, then make it the default for a presentation.
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Add a text box to your presentation and change it however you want.
You can change the font and font size, add a border to the box, and so on.
Select the text box.
Choose Format > Advanced > Set as Default Text Box Appearance (from the Format menu at the top of your screen).
You can change the default whenever you want, and it won’t affect any text boxes already in the presentation.
If you want to apply the same design changes to other text boxes that already exist in the slide, you can save the default text box style as an object style, then apply the object style to other text boxes.