How to Change Clock to 24 Hour Format from 12 Hour in Windows 10?
Start Control Panel, and then under Clock, Language, and Region, click Change date, time or number formats. On the Formats tab, under Date and time formats, do one of the following: To change to 24-hour format, on the Short time drop-down list, select HH:mm and on the Long time drop-down list, select HH:mm:ss.