One of the quickest and easiest ways to make site-wide changes to the words being displayed on your site is to edit the Field Labels.
You can di this by going to SETTINGS >> FIELD LABELS in the admin of your site.
On this screen, you'll see a search bar that allows you to search for a specific label. In the example below, I searched for "zip". Four label variables showed up. I went ahead and changed the first one to Postal Code.
The same can be done for city. By searching for “city”, you can quickly find three cases where “city” is being called: