When your file has active content, you can click the File tab to open the Backstage view. There you can learn more about the active content in your file. As shown in the picture, a Security Warning message appears with information about the active content types that have been disabled. You can click links to see Help articles about active content
You can use either option that appears on the Enable Content button when you click the down-arrow. As shown in the picture, two possible options appear. One option is the ability to enable the content to run for all sessions. The Message Bar will not appear when you re-open it, and the file becomes a trusted document. The other option is to allow the active content to run for one session only. This is because it’s considered risky. The Message Bar appears when you re-open files with active content that runs for one session only. For either option that appears, you can use the Advanced Options to determine which active content you want to run.
When you allow the active content to always run, or click Enable Content on the Message Bar, the file becomes a trusted document, which we’ll talk about next.