You can rest assured that Microsoft will not automatically switch to the new theme right away. When upgrading, the default theme is still the taskbar, the Dark Start Menu and the light-colored application window as before.
The Settings app has its own option of Default Windows mode and Default app mode. If Windows selects dark and the application selects bright colors, you are using the default theme. If both are bright or dark, you have selected a light or dark theme.
In addition, Microsoft added new default wallpapers. You can activate on the Insider Build by going to Settings> Personalization> Themes and selecting Windows Light. The Print dialog of Store apps also has a bright theme, which was previously dark.
New theme options in the settings
Microsoft also made a few changes. For Windows 10 Professional users, Pause Updates will be on Settings> Update & Security> Windows Update, making it easy to find and stop updating.
Windows also automatically sets Active Hours to prevent it from restarting when updating for several hours when you are using your computer. If you enable this feature, you do not need to manually set it. New screen capture tools included on October 2018 Update also improved.
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