Ash here from the Shopify team. Welcome to the Shopify Community!
It sounds like you're in need of updating the EIN on your account, and you're absolutely correct that this is something our team will need to assist with. I'm happy to help out! Since the update requires the submission of sensitive information, we'll need to move our conversation to email so that we can authenticate you on the account in question and provide you a secure way to upload the information. I've sent you an email to the email address associated with your Shopify Community account. Please reply to that email, and once I hear back we can proceed with the next steps together.