A character style is a set of font attributes—such as size, color, and styling like bold, italic, and strikethrough—that determines how text looks. When you style text to look a certain way, you can save that look as a custom character style so that you can easily apply it to other text in your document.
Select the words you want to format.
In the Format 
sidebar, click the Style button near the top.
If the text is in a text box, table, or shape, first click the Text tab at the top of the sidebar, then click the Style button.
In the Font section, click the pop-up menu next to Character Styles, then choose a style.
Select one or more words with the formatting you want to save as a style.
In the Format sidebar, click the Style button near the top.
If the text is in a text box, table, or shape, first click the Text tab at the top of the sidebar, then click the Style button.
In the Font section, click the pop-up menu next to Character Styles, then do one of the following:
Create a new style with a new name: Click 
in the top-right corner of the Character Styles menu, then type a name for the style.
Create a new style based on an existing style: Move the pointer over the style name in the list, click the arrow that appears, then choose Redefine from Selection (characters that used the original style aren’t changed).
Type a name for the style.
Note: To create a character style from text with a background color, select only part of the text, not a full paragraph or heading.
If you change the appearance of characters that have a character style applied to them, an asterisk, and in some cases an Update button, appears next to the style’s name in the Character Styles pop-up menu. This indicates that the style has an override for those characters.
If you want to keep the overrides without updating the style, do nothing. The text retains your changes, and an asterisk appears next to the character style name whenever you select the text.
If you don’t want to keep the overrides, you can revert back to the original character style, update the character style with your changes, or use the overrides to create a new character style.
Select one or more words with the character style you modified.
In the Format sidebar, click the Style button near the top of the sidebar on the right.
If the text is in a text box, table, or shape, first click the Text tab at the top of the sidebar, then click the Style button.
In the Font section, click the pop-up menu next to Character Styles.
Do one of the following:
Update the style to use the overrides: Click the Update button (if there is one), or move the pointer over the style name, click the arrow that appears, then choose Redefine from Selection. All text in the document that uses that style is also updated.
Remove the override: Click the style name in the list. The changes that caused the override are removed.
Click in any text, then in the Format sidebar, click the Style button near the top.
If the text is in a text box, table, or shape, first click the Text tab at the top of the sidebar, then click the Style button.
In the Font section, click the pop-up menu next to Character Styles.
Move the pointer over the style name, click the arrow that appears, then choose Rename Style.
Type a new name for the style.
Click in any text, then in the Format sidebar, click the Style button near the top.
If the text is in a text box, table, or shape, first click the Text tab at the top of the sidebar, then click the Style button.
In the Font section, click the pop-up menu next to Character Styles.
Move the pointer over the style name, click the arrow that appears, then choose Delete Style.
If the style is being used in the document, you see an alert and can choose a replacement style.
If you often use a character style, you can create a keyboard shortcut to apply the style.