There is no right or wrong answer here, if indeed you have a number of customers in both Sweden and the US. If your primary focus is the domestic market, then selling in SEK would probably be the right currency to choose, but if you are looking to expand into the US market and feel that you'll be able to enjoy more growth and revenue there in the long term, then having USD in your primary currency may be beneficial.
You should also be aware that if you're using Shopify Payments, you can accept payments in multiple currencies. This would mean if you have SEK as your primary currency, you can also allow customers in the US to view prices in USD, and to checkout and pay in USD as well. This might be worth considering if you're looking to sell in multiple markets around the world.
Victor | Shopify Social Care
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