To add a logo navigate to Settings > Brands > Click the plus button to add a new brand or click on the brand you want to add a logo.
Click the + Upload a logo option.
Logos preferred Size is 450x450
Max Image Size is 500
This is also where you will add or change your company brand name.
If changing a logo you already have uploaded hover over the current logo and click on the clear or change options.
Below the logo and name you have the option to set as default, choose currency, date format, company phone, email, website, address and an about us section.