To work in the first mode – you must select one of the offered fiat currencies in which payment acceptance is available as the store currency. Remember that in order to start accepting in another currency, you will need to change this setting both in the bot and in your store.
To work in mode two (type 2) and in mode three (type 2) – you need to specify USDT in the store settings. You can leave the “Payment currencies” field empty, because it works as a restriction, not as an allowance. If it remains empty, all active currencies in the StreamPay system are available to you. If you specify some fiat currencies, then your store will work ONLY with the selected currencies, and all new ones will be unavailable to you until you add them yourself. (see screenshot)