You have already known how to create your own AAD tenant, but it sometimes causes some issues. As you know, all Azure subscriptions should be associated to an AAD tenant. You should change the AAD tenant of your subscriptions when you create new AAD tenant. You can learn how to change AAD tenant associated to your subscriptions in this post.
Step by step how to change AAD tenant in Azure portal
Choose your subscription need to change AAD tenant and click "Change directory" button like below.
Choose your new AAD tenant should be associated your subscription.