When you add integrations into the ACCOUNT LEVEL tab here, you can use these integrations for ALL of your stores:
Here is where you can add multiple AutoResponders and multiple Payment Merchants so you can then hook these up to your individual stores. Please note, each store can only have 1 AutoResponder and up to 3 Payment Merchants.
For an existing store, you can go to MAIN STORE SETTINGS > INTEGRATIONS and hook up previously integrated accounts such as AutoResponders and Payment Merchants:
You can select the AutoResponder of your choice for that specific store as well as Lists from that AutoResponder account.
You can also select your payment merchants here, you can select up to 3 payment merchant options for your store.
PLEASE NOTE: you also have the opportunity to select the desired AutoResponder and Payment Merchant accounts upon launching a store, but it is not required to do so at that step. If you do not add those integrations while launching your store, you would do it here within the Main Store Settings of your store.