You can edit the barcode label by going on Menu > Settings > Products > Barcode Label
About the configuration preview :
You have to define in first the "Sku for label preview" and the "Warehouse for location' fields in order to get a preview of barcode depending on the correct warehouse.
Note that the warehouse chosen here will be used every time you will generate a new product barcode label from Connect.
About the position and Size :
- Barcode :
- Barcode Position : x, y
- Barcode Size : Height and Width.
- Other :
- Position : x, y
- Size : Font size