My name is Lilith, I'm on the Social Care team at Shopify.
You're able to switch between accounts on Shopify easily with the new single sign-on we've implemented.
If you're switching between stores you can use our guide here to help you ensure that you're using the correct dropdown to switch between your accounts.
Let me know how you do with the information above! I'm happy to answer any questions you think of as you work on your business.