Can't find refresh button in Solution Explorer

Hi,

I am using Visual Studio Community 2015 Version 14.0.25123.00 Update 2. And my operation system is Windows 10 Home edition. In my Solution Explorer, however, I can not find the refresh button! Currently I have a "Back" button, a "Forward" button, a "Home" button, an "Open Files Filter" button, a "Sync with Active Document" button, a "Collapse All" button, a "Show All Files" button, a "Properties" button, and a "Preview Selected item" button. Where is my "Refresh" button? How can I set it up?

Thanks a lot!

Jeff