Warning: Trusted Documents open without any security prompts for macros, ActiveX controls and other types of active content ...

Warning: Trusted Documents open without any security prompts for macros, ActiveX controls and other types of active content in the document.  For a Trusted Document, you will not be prompted the next time you open the document, even if new active content was added to the document or changes were made to existing active content. Therefore, you should only trust documents if you trust the source.