How can you configure the default sign-in tenant for the Azure portal if you have multiple Azure Active Directory tenants?

To configure the default sign-in tenant for the Azure portal when you have multiple Azure Active Directory (AAD) tenants, changing the directory from the Azure portal is the correct approach.

When you navigate to the Azure portal, there are options available in the account settings for managing the directories you can access. By selecting a specific directory as the active directory, this setting will dictate which tenant will be the default when you next log in. This method is straightforward and directly integrated into the portal environment, making it user-friendly for administrators managing multiple tenants.

In contrast, while it may seem intuitive to adjust portal settings or use command-line tools in Cloud Shell to change the context of the subscription or the Azure environment, these methods are not aimed specifically at setting the default sign-in tenant for the portal itself. Running commands like Set-AzureRmContext or Set-AzureRmSubscription primarily facilitates configuration of the context within PowerShell or Cloud Shell sessions, rather than altering the default tenant for the Azure portal sign-in experience.

As a result, selecting the appropriate directory through the Azure portal provides a clear and direct method of establishing the default tenant context for sign-ins, making it the most effective choice.