Step 1: Log into the Drupal 8 admin interface.
Step 2: Using the top menu bar, click on the Menu option.
Step 3: This leads to a second menu bar appearing under the first. From here, click on the Configuration tab.
Step 4: Look for the Regional and Language category and then click on the Regional Settings option.
Step 5: Here you will see a dropdown from which you will select your site’s default time zone.
Step 6: Once you have selected the preferred time zone, click on the Save Configuration button at the bottom to activate your changes.