Since migrating from Google Merchant Center Classic to Google Merchant Center Next, the person who clicked the migration button has magically become the super admin. That is not the expected behavior. For example, I manage many accounts and do all day-to-day tasks for my clients, including migrating accounts. In these cases, my clients need to be the super admin, not me. So, in this case, I have to now update all the settings to send my clients an update to become a super admin.
How can I update the settings?
Log in to Google Merchant Center Next
Go to the cog icon > select People and Access
Here you can see, that I am the super admin
On this page, click on Manage in Business Manager
Now click on Manage next to your clients email address or whoever you want to add the super admin access to.
Click on Add Access
Now check the radio button for the user to become a super admin
