Many dialogs in Visual Studio don’t remember their size and position, always opening with the same size. If this default size is small, each time you need to manually resize it to make usable. One of these dialogs is Refactoring – Rename – Preview Changes:
Preview changes dialog in Visual Studio 2013
Remember Window Size extension remembers size and position of the Preview Changes window after you resize it and restores it when you open the window next time. This functionality is supported for Visual Studio 2010, Visual Studio 2012 and Visual Studio 2013.
https://tabsstudio.com/
Making Visual Studio perfect 