I found what is arguable either a bug or a (misguided, IMO) attempt to make the UI 'simpler'. Either way, it's incredibly confusing. What's occurring is that the Configuration->Hardware->Graphics options are not available in the Parallels configuration UI after a certain series of events. Steps to repro: Configure Parallels such that it's running Windows 10 on a Retina Macbook Pro using 2 external displays plus the Macbook display. Go to Configuration->Hardware->Graphics and change the "Scaling" setting to "Scaled" Close the Macbook pro so the VM is only using the external displays. Suspend the VM and exit Parallels. Disconnect the external displays (as if you are leaving your work setup and intending to work from a new location solely using the Macbook). Start Parallels and resume the VM. You'll notice that the display is a little blurry due to being in scaled mode. Now go to Configuration->Hardware->Graphics and change "Scaling" to "Best for Retina Display". This will cause a logout of the Windows 10 account. Log back in and observe it's not using the retina resolution. Suspend the VM and exit parallels Re-connect the external displays Close the macbook so it's running only on external displays Start parallels and resume the VM. Go to Configuration->Hardware->Graphics and attempt to change "Scaling" back to "Scaled". **** THE BUG **** you'll notice that there is no "Scaling" option available, only "Advanced Settings" !!! Suspend the VM and exit parallels Open the Macbook so you're using all 3 displays Start Parallels and resume the VM Go to Configuration->Hardware->Graphics **** You'll notice that the "Scaling" option is now available in the UI. So the basic issue seems to be that the "Scaling" options are not available unless the Retina display was active at the time Parallels was started? I find this very confusing and frustrating, because there's no indication of how to change your resolution settings back again unless you happen to randomly start up Parallels with the Macbook display open again. Suggestion: do not hide the "scaling" options if the Retina Macbook is closed. Instead disable them with a message indicating why they are disabled.