The Header block sits at the top of your pre-checkout page. It shows your store logo or name so customers know where they are.
The Header is a required block — it's always on the page and cannot be removed, you can hide it if you want though.
Settings
Custom logo — Toggle on to upload a custom logo for the pre-checkout page. When off, the page shows your store's brand logo from Shopify (set in Settings > Brand in your Shopify admin). If no brand logo is set, your store name is displayed as text instead.
Logo — Upload or select a logo image. Only appears when Custom logo is turned on.
Tips
Square or circular logos work best. The logo displays at a compact size, so avoid images with small text.
If you want the same logo across all your pre-checkout pages, set it once in Shopify under Settings > Brand rather than uploading a custom logo on each link.