Hi there! I understand your Hiya app screen freezes and becomes unresponsive right after the new update on your iPhone running iOS 18.6. Let's work through this step-by-step to get it back to smooth operation.

First, just to confirm, have you tried closing the Hiya app entirely and reopening it? On your iPhone, you can do this by swiping up from the bottom and pausing in the middle of the screen to bring up the app switcher, then swipe the Hiya app off the top to close it.

If that doesn’t help, the next simplest step is to restart your iPhone. A fresh restart can clear any temporary glitches the update might have caused.

Assuming those basics didn't solve it, the best next step is to uninstall and then reinstall Hiya. This often clears up any corrupted files from the update. Here's how:

1. Press and hold the Hiya app icon until a menu appears or the icons start jiggling.
2. Tap "Remove App," then confirm "Delete App."
3. Go to the App Store, search for “Hiya,” and reinstall it.
4. Open the app and check if it runs smoothly now.

If the screen still freezes after reinstalling, please let me know. We can try checking if there are any specific app permissions or iOS settings that may interfere with the app, or if there might be a known issue on our side.

Does this sound good to start with? Let me know how these steps go!