SketchUp does not yet support Windows 10. *
(Notice that Windows 10 is not yet listed on the Hardware and Software Requirements page.)
The Admins have pinned a prominent warning post in the SketchUp category, which you should read:
Early Adopters (of New OS Versions) Be Cautious
* FYI: SketchUp 2015 was released last Nov in 2014. Windows 10 was just released 30 days ago.
All that said, use the mouse to grab the scroll bar handle (pip, whatever it is called,) and manually slide it. Or click just above the handle to page up, click below the handle to page down. You do not need to select a template every time you start SketchUp. Selecting one makes it the default template.