How to Add and Edit Slide Text in Keynote
As with other iWork applications Pages and Numbers — which also use boxes for text layout — Keynote allows you to add or edit text with ease. For example, double-click in a box with the text Double-click to edit, and the placeholder text disappears, leaving the field ready to accept new text. Any new text you type appears at the blinking cursor within the box.
To edit existing text in your Keynote document, click using the bar-shaped cursor to select just the right spot in the text, and drag the insertion cursor across the characters to highlight them. Type the replacement text, and Keynote obligingly replaces the text that was there with the text you type.
If you want to delete existing text, click and drag across the characters to highlight them; then press Delete. You can also delete an entire box and all its contents: Right-click (or Control-click) the offending box and choose Delete from the menu that appears.
When the contents of a box are just right and you’re finished entering or editing text, click anywhere outside the box to hide it from view. You can always click the text again to display the box later.