How do I stop Windows from changing time?

To prevent it from changing, disable time syncing.
  1. Right-click the time and date display on the right side of the Windows taskbar and select “Adjust Date/Time.”
  2. Open the “Internet Time” tab in the “Date and Time” dialog box that opens up and then click the “Change Settings” button.

 

Why does Windows 10 keep showing the wrong time?

Windows Time Is Out of Sync

You should first confirm that your computer is syncing its clock with a valid time server. To do this on Windows 10, head to Settings > Time & Language > Region, then choose Additional date, time & regional settings from the right side.