Hi there! I see you’re having trouble signing into the MyQuest app to make an appointment on your iPhone running iOS 18.6. Let’s get this sorted out together.

First, to help me find the best solution, can you tell me:
- Are you seeing any specific error messages when trying to log in?
- Have you been able to log in successfully before, or is this your first time?
- Have you already tried resetting your password using the "Forgot Password" link?

Meanwhile, here’s a step-by-step approach we can try:

1. Verify your login credentials: Make sure you are entering the correct username and password. Passwords are case-sensitive on MyQuest.
2. Reset your password: If you’re unsure or getting an “invalid password” error, use the 'Forgot Password' link on the login screen to reset it. You’ll receive an email to create a new password.
3. Check for app updates: On your iPhone, open the App Store, tap your profile icon, then scroll to see if an update is available for the MyQuest app. Installing updates may fix login issues.
4. Force close and reopen the app: Sometimes, closing the app completely and reopening it helps clear temporary glitches.
5. Restart your phone: This can resolve network or app-related hiccups.
6. Ensure stable internet connection: Check if your Wi-Fi or cellular signal is strong and working properly.
7. Clear app cache/data: Although iOS apps don’t have a direct cache-clear option, you can try uninstalling and reinstalling the MyQuest app to refresh it.

If these steps don’t resolve the issue, it’s possible there could be a problem on the server side or something specific with your account. In that case, I can guide you on how to reach MyQuest support directly or check for known outages.

Could you please try these steps and let me know what you find? Also, sharing any error messages or behaviors will help me assist you further.

Are you comfortable trying these now?