After you've created your custom branding, you can go back and change anything you want.
To edit your custom branding
-
Sign in to the Azure portal using a Global administrator account for the directory.
-
Select Azure Active Directory, and then select Company branding, and then select Configure.
-
On the Configure company branding page, add, remove, or change any of the information, based on the descriptions in the Customize your Azure AD sign-in page section of this article.
-
Select Save.
It can take up to an hour for any changes you made to the sign-in page branding to appear.