Change the link underline color in Keynote
Select the text, press CMD-T to open the Fonts panel (from the Format > Font menu), then change the underline color via the underline popup's Colour menu item.
Please see image below.
Select the text, press CMD-T to open the Fonts panel (from the Format > Font menu), then change the underline color via the underline popup's Colour menu item.
Please see image below.