So that we can try to best assist you, please provide the url of the site you’re working on,
as well as point out the particular headings on your site you are wanting to modify.
You can accomplish this via custom.css or creating a “local” folder.
By default, there should be one ‘custom.css’ file in /templates/purity_iii/css folder. However, if you want to customize one theme in this template and don’t want to loose these custom work when updating template, you can customize any theme via: /templates/purity_iii/local folder.
We’ve recently implemented a new feature in new version of T3 framework so that customer can add custom work in a folder which can’t be affected when updating template. You can check out this documentation for more information: http://t3-framework.org/documentation/new-features#isolate-template