HTC One (M8) for Windows
Check for System Updates - HTC One (M8) for Windows
Check for System Updates - HTC One® (M8) for Windows®
From the Start screen, swipe left to display the Apps list.
(located in the lower-right; may require scrolling to the bottom of the Start screen).
Ensure the following setting is configured as desired:
Enabled when a check mark is present.
Automatically download updates if my data settings allow it
check for updates