How to add or change website’s logo
You can add a logo for your whole website from Theme options > General Settings > General: Or you can set a logo for a specific header from the header builder (WordPress Admin Panel > Headers > Edit your desired...
How to set page or post thumbnail
You can set the page or post thumbnail by adding a featured image in WordPress (from Edit Page or Edit Post page) as following:
Customize page intro section
Learn how to customize the page intro section in your different website pages.
How to disable post featured image
You can hide the post featured image from the top of the post by adding this code snippet into Theme options > Layout > Advanced > Custom css: