types of text boxes
Keynote has two types of text boxes:
Two-handled: A two-handled text box displays two selection handles (white squares) when it’s selected, and resizes automatically when you add text. Text boxes you add using the Text Box button in the toolbar are two-handled text boxes.
Eight-handled: An eight-handled text box displays eight selection handles (white squares) when it’s selected. These text boxes don’t resize automatically when you add text. Most of the placeholder text boxes that come with a theme are eight-handled text boxes.
Note: To convert a two-handled text box into an eight-handled text box, choose Format > Shapes and Lines > Reset Text and Object Handles (from the Format menu at the top of your screen).