On the Mobile Sales App, the Price List and Tax Type assigned to that Customer will be applied to the Order by default. Also, if the Tax Type has been assigned to the variant, it will be reflected in the Cart too. For example, non-taxable products will add to the Cart with 0% tax when creating an order.
The product catalog will also display all prices according to this Price List.
If you do not want the Default Price List and Tax Type which has been assigned to the customer to be auto-populated, go to Dashboard> More> Settings section of your iOS app and Select the option to “Ignore Customer Defaults”.
After you have enabled this, Orders that are created in your cart will be assigned to the Price List and Tax Type selected in the Settings section instead of using the Customer's defaults options.