Members on auto-renew keep paying in the currency they agreed to
If you change your workspace’s currency, each member’s auto-renewal stays in the currency it was made in. A dues price change moves only the renewals in the currency of the new price, and only those members are told of it; everyone else keeps the price they agreed to. Each renewal reaches Money in your books’ currency: what was charged, when it was charged in it; otherwise what Stripe paid into your balance in it; otherwise it is left out of the books and named on the month’s Overview, so you can record it at your bank’s rate. The member’s receipt says what they paid, in the currency they paid it in. Settings → The Basics says all this beside the Currency box.