Please go to your wp-admin panel and follow the instruction for add mobile logo:
- Go to Appearance Menu > widgets
- Here you found some widget position, please go to logo small widget position
- Add a logo widget here
- Drag a this logo widget and drop it in small logo position. Then add image of logo.
- Then click to save
- For more help please follow this image:
- You are done ?
- please check your site from mobile/make your browser small width