To help improve security in Office, Microsoft is changing the default behavior of Office applications to block macros in files from the internet.
With this change, when users open a file that came from the internet, such as an email attachment, and that file contains macros, the following message will be displayed:
Guidance on allowing VBA macros to run in files you trust
Remove Mark of the Web from a file
For an individual file, such as a file downloaded from an internet location or an email attachment the user has saved to their local device, the simplest way to unblock macros is to remove Mark of the Web. To remove, right-click on the file, choose Properties, and then select the Unblock checkbox on the General tab.
In some cases, usually for files on a network share, users might not see the Unblock checkbox for a file where macros are being blocked. For those cases, see Files centrally located on a network share or trusted website.