Your General settings page controls the date and time displayed on all posts and comments.
The default timezone settings on all newly created sites is UTC (Coordinated Universal Time) which is in London, UK. All posts and comments are automatically time stamped as UTC time unless you change your timezone.
You change your date and time settings in Settings > General by selecting a city in the same time zone.
Select your preferred date format.
Select your preferred time format.
Then click Save Changes.
This automatically updates the timestamp on all published posts and comments to your timezone.