On an iOS device, this is how you change the order in which products are displayed.
Go to the Settings app. Scroll down till you see ‘Onsight’ on the left. Tap on ‘Onsight’. On the right, tap on ‘Sort By’. Choose between ‘Name’, ‘Barcode’, ‘SKU’ and ‘Product Code’. Go back. You can also specify ‘Sort Direction’. This will determine how your products are displayed within each category. The product categories themselves are displayed alphabetically.