Customisations to the product page
Your theme's product page is where full information about a product is displayed.
You can make certain small changes to this page using the product page settings in the editor. (You can access the style editor by clicking 'themes' on the left menu and then 'style editor' for the theme you would like to customise).
Scroll to the 'product page' section. The exact settings available here will depend on the theme you are using.
Make your changes and click the 'save changes' button at the bottom of the page. You should then check your website to make sure the changes have been applied and are working as expected.