Hey there Janice-heron,
By default, the date and time, visible on the Lock Screen, are set automatically based on your location. If you want to change them—for example, when you’re traveling—you can adjust them using the following steps.
1. Go to Settings > General > Date & Time.
2. Turn on any of the following:
* Set Automatically: iPhone gets the correct time over the network and updates it for the time zone you’re in. Some networks don’t support network time, so in some countries or regions, iPhone may not be able to automatically determine the local time.
* 24-Hour Time: (not available in all countries or regions) iPhone displays the hours from 0 to 23.
Read more here:
Change the date and time on iPhone
If you have any issues, follow the steps in this link:
If you can't change the time or time zone on your Apple device
Regards.