These are settings which affect all of the pages of your site, so you can edit them in the Theme Customizer.

Using the Footer Builder

With the Theme Customizer open, scroll down to the footer and hover your mouse over the area you want to edit. You'll see a blue pencil icon appear. Click it to edit that part of the footer.

Here's a video tutorial for the Footer Builder:

Using the Header Builder

In the Theme Customizer's left menu, click Header Builder:

Here's a video tutorial for the Header Builder:

Changing your logo(s)

For the logo, you may need to upload two versions of your logo if some of the pages of your template have a transparent header and some don't.

For example, some templates have the logo as black text on a solid white header for the blog posts, but the main pages have a transparent header with a dark image behind it. In this case, the black text would be hardly visible, so it's set to use a different version of the logo (with white text) for the pages with a transparent header.

In the Header Builder, you can change the main logo by clicking Site Title & Logo. To change the logo in a transparent header, click Transparent Header.

Additional reading: How to Manage Your Site Identity (logos, site title, tagline, etc.) in the Header Builder

And you can always reach out to support if you have specific questions. We'd be happy to help!