We do not recommend changing currency after making your first sale, as Stripe does not allow users to make purchases in multiple currencies.
Once a customer has been created in Stripe, Stripe will not allow that same customer to make a purchase in a different currency. For example, this means that if a user paid for a course in USD and you changed your currency to CAD, they would need to create a new account in order to make the CAD purchase.
If you're not concerned about users making multiple purchases on your site, you'll want to head to your Stripe integration page to update your currency. Then, you'll need to edit any courses or bundles that you're selling and re-save your prices, as Thinkific will send the new currency data to Stripe when you save your price.
Failure to do this will result in Stripe payment failures as if a user tries to purchase a course after you've changed your currency, Thinkific would try to connect the user to a plan that was in your previous currency which no longer exists.
Changing your currency will not impact any users that have already purchased subscription or payment plan products. Those users will still pay in your previous currency.