The available options in the rich text editor vary by question type and field. To see the options available for a particular field, click directly into the field.
To format text:
Themes and CSS themes (Enterprise only) let you apply text formatting across your entire survey. The rich text editor lets you edit text in individual fields, one place at a time.
You can change the font size and style in your theme settings to control survey-wide text formatting. You can use the rich text editor to add additional formatting or to override the theme font settings for an individual text field. Save your changes to see the formatting applied by theme and the rich text editor in the survey.
Formatting text using themes or the rich text editor adds HTML tags that count toward character limits.
Some standard themes have bold question text by default. In this case, you need to change the font settings of your theme and uncheck Bold under Question Text so you can go back and bold specific words in your question.