If you're experiencing error messages and issues after updating to the 64-bit version, you may have incompatible 32-bit add-ons.
Solution 2 Try removing any proxy settings, you can do this by following these steps. If there isn’t a newer version or if you don’t need to use the add-in you can leave it unchecked.These popular add-ins are known to cause problems with Office 2016 for Mac 64-bit if you have the 32-bit version installed.You use it to navigate to Web sites, and it displays those sites for you, allowing you to follow links and explore everything the web has to offer.There are many different browsers available, but four of them account for over 95 percent of all browsers in use today: Internet Explorer, Firefox, Chrome, and Safari [source: Stat Counter].
You'll see Internet Explorer updates listed under "Important Updates." If Windows is set to update automatically, then IE will be kept up to date as well.