Our app uses your shop's default currency to configure your flat rate rules.
If you change your shop's currency after configuring rules in the Vendor Shipping Rules app, you must go back into your rules and adjust the prices to be accurate in that currency. The values for the shipping costs will remain the same, but we will now pass those values along to Shopify as being in your native currency.
Because we cannot detect your shop's default weight unit you must set your preferred weight unit in the app's settings section.
Both Shopify and our app use 'grams' as the canonical weight unit. That means whatever weight/unit you enter in our app is converted to grams and then compared to whatever weight/unit you use in Shopify converted to grams for the final calculation. So you can have some products in Shopify set-up with pounds, kilograms, ounces, or grams, and we'll automatically match those values up with whatever values you set-up in our app.