Changing .properties file

Can someone tell me why whenever I change String to display in .properties file it does not change on the gateway? It stays the same as it was before.

BundleUtil loads property files. For the bundles you manually load during setup and unload during shutdown, you can control the lifetime. However, some property files are loaded on demand when a class loads and you have no control over the lifetime. After you change those, you have to restart Ignition itself.
Also, strings loaded into a wicket session can remain serialized with the old values until the session expires. I believe there’s a way to expire wicket’s strings early, but I don’t recall.