Answer
Select a hashtag, add your own request and send with @ai on. Typing a new hashtag name alone does not save a macro. Hashtags have Text, Image, Video or Audio types, and the picker follows your selected type.
Public hashtags can be discovered by others. Private hashtags are available only to their creator, but their resulting messages still follow the chat’s visibility. A private hashtag does not make a group response private.
Do not put secrets in public prompts. Public search results can expose prompt content, including when a description is empty. A manual selection applies to an accepted request; use Universal Hashtags for persistent chat defaults.