I have a dual boot Windows 10 Pro/Ubuntu 18 laptop. Every time I reboot from Ubuntu to Windows, Windows sets my system clock ahead by 8 hours and says it is California time.
I am a Windows Insider, and I complained about this bug for several years with no results. I guessed that Windows PowerShell would be able to control the clock. A Google search gave me a link to a detailed description of the Set-Date command: https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/set-date?view=powershell-6
An example showed exactly how to adjust the system clock. Execute PowerShell in administrative mode: