There is a bug in Revit 2017 on Win10 whereby if Dynamo is installed then the Quick Access Toolbar is invisible when above the ribbon. When you uninstall Dynamo the QAT appears above the ribbon. The workaround is to set the QAT to be below the ribbon if you dont want to uninstall Dynamo.
Obviously we don't want people to uninstall Dynamo to make Revit QAT work.
I've had two laptops and both did the same.
Here is the forum entry with other guys having the same issue:
http://forums.autodesk.com/t5/revit-architecture-forum/quick-access-toolbar-invisible-in-windows-10/...
Thanks