Hi there! I see you're having trouble registering on the Stealth Fitness app on your iPhone with iOS 18.5. Let's figure this out together.

Could you tell me a bit more about what happens when you try to register? For example:
- Do you see any error messages?
- At what step does it stop?
- Are you connected to Wi-Fi or using cellular data when trying to register?
- Have you tried closing the app completely and reopening it?

This will help me guide you better. Meanwhile, here are a few initial steps you can try:

1. Force close and reopen the app: Sometimes the app gets stuck. Double-click the home button or swipe up from the bottom (depending on your iPhone model) to bring up the app switcher, then swipe the Stealth Fitness app off the screen to close it. Then reopen it and try registering again.

2. Check your internet connection: Make sure you have a stable internet connection. You can try toggling Wi-Fi off and on or try registering via Wi-Fi if you're on cellular and vice versa.

3. Restart your iPhone: A simple reboot can clear temporary glitches. Press and hold the power button and volume button until you see the slider, then slide to power off. Turn it back on after a minute and try again.

4. Update the app: Make sure the Stealth Fitness app is up to date from the App Store. Sometimes registration issues are fixed in updates.

If you have tried these already, let me know, and we can try deeper troubleshooting like checking app permissions or even reinstalling the app without losing your data.

How does that sound? Can you try these and tell me what happens?