If you wish to see a specific part of the design in the colorway preview and thumbnails, here you can use the feature to customize the offset in the preview. Thumbnail previews will be regenerated using the new offset of the origin.
When opening a colorway you can move it graphically, changing, therefore, the offset.
Such change can be saved from the '...' button and the unfolded option 'Save current offset' below the preview. 
You can go anytime back to the original offset or go back to the custom offset with the icons below the preview.