You can set a logo and update it under Settings > Style.

If you are using the default HTML styles, after you upload a logo it will automatically appear in the header of your knowledge base. If you accidentally deleted the markup for the logo you can use:

<a class="navbar-brand" href="/help" alt="Logo" title="Your site">[example("project-logo")]</a>

Replace the word "example" with "template" in the merge code. This merge code will pull in the markup for the image automatically.

Does my logo have to be a certain size?

With CSS overrides we can resize any image to fit after upload, but we recommend using an image that is no taller than 60px and no wider than 300px.