You can learn how to add your logo to shipping label templates.
1. Open Easy Invoice+ from Apps section of your Shopify store or go directly to https://easyinvoice.softify.co/
2. Click “Shipping Labels” from left menu.
3. Edit your primary shipping label template.
4. Click “Choose File” from left settings panel of Shipping Label template and choose your logo from your computer.
5. Click “Save” button.
Suggested logo size is 150×100 pixels but Easy Invoice+ can also auto resize your logo to your Shipping Label template.