Keynote includes built-in paragraph styles that specify a font and font size, color, and other attributes for text. These paragraph styles are designed to match the theme of your presentation. Applying paragraph styles to text ensures a consistent look for the text in your presentation.
If you make changes to text that uses a paragraph style, you can create a new paragraph style based on the changes. For example, if you change a paragraph that uses the Subtitle style so the text is blue and bold instead of regular black text, you can create a new paragraph style Subtitle 2 that incorporates the changes. You can then easily apply the new style to other text in your presentation.
Note: Keynote also includes built-in character and list styles. These styles are similar to paragraph styles, and the tasks below apply to character and list styles as well.
Select the text or shape with the text you want to change.
In the Text pane of the Format inspector, click 
at the top of the pane, then choose a style from the Paragraph Styles menu.
Select the text you want to base your new paragraph style on.
In the Text pane of the Format inspector, click the paragraph style name at the top of the pane.
Click 
at the top of the Paragraph Styles pop-up menu.
Enter a name for the new style, then click outside the menu to close it.
You can assign a shortcut key (F1-F8) to a paragraph, character, or list style.
In the Text pane of the Format inspector, do one of the following:
For a paragraph style: Click the paragraph style name at the top of the pane.
For a character style: Click the Character Styles pop-up menu.
For a list style: Click the Bullets & Lists pop-up menu.
In the pop-up menu, move the pointer over the name of the style you want to assign a shortcut to, then click 
.
Choose Shortcut, then choose a key.
Now, the shortcut key appears next to the style name in the menu for easy reference.
To use a shortcut, select text, then press the Fn key and your shortcut key (for example, F1).
To remove a shortcut key assignment, choose None from the Shortcut menu.
When you change the formatting of text that has a paragraph style applied to it, an asterisk appears next to the style name at the top of the Text pane of the Format inspector. This asterisk indicates the selected text has been modified from its original style. If you don’t want to keep the changes (the overrides), you can revert to the original style.
Click the paragraph with the override.
In the Text pane of the Format inspector, click next to the paragraph style name at the top of the pane.
Click the style name (it has a gray checkmark to indicate an override).
The override is cleared and the text reverts to the original style.
If you change the formatting of text that has a paragraph style applied to it, you can update that style to reflect your changes. You can use the new paragraph style to format other text.
In many cases, when a style can be updated, you see an Update button next to the style name at the top of the Text pane. Click the button to update the style. If you see an asterisk next to the style name instead, you can still update the style.
Click the paragraph that uses the style you want to update.
In the Text pane of the Format inspector, click the paragraph style name at the top of the pane.
In the Paragraph Styles menu, move the pointer over the style name, (it has a checkmark), then click the arrow that appears.
Choose Update Style.
You can just copy the style of selected text and apply that style to other text.
Select text, then choose Format > Copy Style (from the Format menu at the top of your computer screen).
Select other text to apply the style to, then choose Format > Paste Style.
If you copy text and want it to match the style of the text where you’re pasting it, choose Edit > Paste and Match Style (from the Edit menu at the top of your computer screen).
Click a paragraph that uses the style you want to rename.
In the Text pane of the Format inspector, click the paragraph style name at the top of the pane.
In the Paragraph Styles menu, move the pointer over the style name, (it has a checkmark), then click the arrow that appears.
Choose Rename Style, then enter a new name.
You can delete a style that isn’t being used in your presentation. If the style is being used, you can designate a replacement style for it.
Click any text.
In the Text pane of the Format inspector, click the paragraph style name at the top of the pane.
Move the pointer over the name of the style you want to delete, then click the arrow that appears.
Choose Delete Style.
If you try to delete a style that’s being used, you’re asked to choose a style to replace the one you’re deleting.