I've forced to uninstall Parallels Tools to disconnect the relation between MAC screen resolution and WIN screen resolution, BUT I've lost the Audio driver and the Networking between MAC and WIN, Until I found the solution. I tried to play with WIN settings and screen resolution and MAC screen resolution. and microscopic context menus as will, I cannot use the WIN like this. the screen resolution is SO high because of the Retina setting on MAC. The problem's started when I've setup Parallel Desktop 9 and installed WIN 8.1, after that I've installed the Parallels Tools. Just forget about all the old advises and read this. As unfortunate as it sounds, the best browser on Windows for retina resolution / DPI is Internet Explorer 10. It all depends on the program you are using. Windows does its best to fix these issues by bitmap scaling the Window, and translating input, but it won't ever be perfect and it will look like a JPG that's 200% zoomed. It's very bad practices for developers, but some of them always assume a fixed number of points-per-inch, like 96. The next problem is that Windows does DPI scaling differently - some programs do not respect Windows DPI scaling. Windows can't change it's DPI without a full logout / login - so if you change displays you'll have to log out of Windows and log back in. The only trick to this is when you connect to an external display and you want to show your Parallels VM there. The next time you reboot, Windows will have its DPI set to 199% (why not 200% I'm not sure). You can do this under your Virtual Machine's configuration, Hardware, Video Options, and select 'Best for Retina'. Since you are using a Retina MBP - which has an extremely high resolution, you'll want Parallels to manage the DPI of your Windows VM. I've seen this particular problem many times, and a lot of it has to do with how Windows handles DPI scaling.

Parallels update problems