Whenever you open a file which was downloaded from the Internet, like a Word File or an Excel file it always opens in Protected view. In this mode one cannot edit the file unless you trust it. This is the default precautionary measure taken by Windows. This is quite acceptable given the amount of Malware on the Internet.
But all files which are from the Internet are not Malware. Some files are the ones you trust especially which come from your friends and family. You would not want to open them in Compatibility Mode, Do You? Fortunately Windows has a solution for this, it is called the Trusted Host Location.
A Trusted Host Location is a path to a folder in your computer. Any files which would go into that folder are the ones you trust. When you open any file from that Folder, it would open in the Edit Mode and not in Protected View because it is coming from a location you Trust.