Customizing main page different from posts

Hi there,

I’m not sure how to explain this, and I wasn’t sure how to search it, so I apologize if you’ve already responded to similar posts.

I’m having trouble keeping the basic layout and design of the main page different from the design and page layout of the latest blog post. For example, I would like to have the title image on the main page, but not on each blog post. I had it all figured out on the main page by adjusting everything in High End Options/Layout Settings/Default Settings, but when I removed the title image from the blog posts, the main page lost the image as well.

Secondly, is there a way to create a master template for all blog posts, that way I don’t have to alter the custom settings for each new post we create?

And thirdly, I couldn’t find help on how to make a YouTube video be a featured image of a blog post, and therefore show up on the main page.

Thank you so much in advance!