You may notice that the start menu does not display properly in Windows 10. Windows likes to apply a transparency setting to the menus that might affect legibility. To fix that, press the Windows Key+U to go to the Settings panel. Click on Display and turn off Show transparency in Windows
You can also change this using regedit and set HKEY_CURRENT _USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize\EnableTransparency and set it to 0.