You can change the association of the directory to the subscription. https://learn.microsoft.com/en-us/active-directory/active-directory-how-subscriptions-associated-directory#how-an-azure-subscription-is-related-to-azure-ad
There are a lot of tutorials on YouTube for how to do this. This one is not from an official guide, but I think it is pretty straightforward and good.
Note that multiple subscriptions can trust the same directory, but a subscription trusts only one directory. You can go to the Settings tab to see which directory is trusted by your subscription and then edit the subscription settings to change which directory it trusts.