Click on the Highlighter icon to reveal the Keywords panel.
Enter a specific word or phrase you want to highlight in the text box and click Enter. The keyword will then be highlighted in a specific color throughout the current folder. If you want to change the color, click on the color of the highlight and a color palette will appear from which you can select another color. The numbers in parentheses in the colored text box displays the total number of occurrences of that keyword on the current page.
To store your frequently-highlighted keywords for recurring use, click on Save to Keyword Sets.
You can save up to 10 keyword sets that can store up to 40 keywords each. Select an empty set where you want to save the keywords. By default, they are named Set 1 to Set 10, which can be renamed.
There will be a prompt showing whether the keywords were successfully saved or not. The number next to the set name will also reflect the number of keywords.