A Windows sign-in notice appears before a user signs in. It does not change the firmware boot screen, and it should not be described as a way to customize every startup image.
Use the documented policy#
Microsoft documents the interactive logon message text policy. Where the policy editor is available, the related title and text settings are the appropriate place to configure a notice.
On a managed device, ask the administrator before making changes. A domain or device-management policy can override a local setting. The available tools also depend on the Windows edition.
Keep the message short and accurate#
A sign-in notice is not an access-control mechanism, and a decorative message should not make unsupported legal claims. Check line breaks and readability, then test the actual sign-in behavior on a device you administer.
Registry editing is not necessary just to understand the feature. Start with the policy documentation and the controls available to your Windows edition. If you are looking for a lightweight place to write daily notes instead, the Notepad work-log guide is a separate, ordinary text-file workflow.
