macOS · Research guidance. Instructions are based on publisher guidance; a UK IPTV account was not tested on this platform.
Consider what the audience can see
A notification banner may reveal more than its app name. Before connecting a Mac to a shared television or presenting a support demonstration, consider whether message text or account details could appear. Use a harmless sample notification rather than waiting for a real private message to test the setup.
Review the global preview choice
Apple documents System Settings, Notifications, with Show previews options including Always, When Unlocked and Never. The global choice acts as a default for individual app previews. Read the current state and decide whether preview text should appear in the situation you are preparing for, including a shared or unlocked screen.
Check relevant app overrides
Apple also documents app or website notification settings that can use Default or an explicit preview choice. Review the messaging and support apps most likely to appear. A global default does not tell the whole story if an individual app has an override; inspect both levels before assuming the displayed content will be hidden.
Keep presentation and retention distinct
Preview choices govern the described notification presentation. They do not delete the underlying message or certify that no other window contains private information. Close unrelated content and test the actual shared view with a non-sensitive example. If a Focus is also in use, treat its delivery choices as an additional control rather than a substitute for checking preview text.
Questions, answered
Can an app override the default preview setting?
Apple documents individual app preview choices as well as the global default.
Does hiding a preview delete the message?
No. Presentation and message storage are separate matters.