Magento 2.0.X change favicon
1. Login to your Magento Admin Panel.
2. Click on STORES tab from the left sidebar.
3. Click on Settings => Configuration section:
4. Click on left hand side => General tab => Design. After that, expand HTML Head tab from the right panel.
5. Now upload your favicon, click on the Choose File button and select your favicon image.
6. When you are done, click on the Save Config to set your new favicon.