Hi there! I understand your UnitedHealthcare (UHC) app screen is freezing on your Mac with OS X 10.15.7. Let's work together to get that fixed. Just to clarify, is this happening when you use the UHC web portal through a browser on your Mac, or are you trying to use a specific UHC app on your Mac? Also, does the freeze happen right after opening, after login, or during certain actions?

Once I know a bit more, I can guide you through the best fixes.

Meanwhile, here are some initial steps to try that often resolve freezing issues on Macs:

1. Restart Your Mac: Sometimes a simple restart clears out temporary glitches.

2. Clear Browser Data: If you are accessing UHC through a browser, clearing cache and cookies can help. For Safari (default on macOS Catalina 10.15.7):
- Open Safari > Preferences > Privacy > Manage Website Data > Remove All.

3. Try a Different Browser: If the screen freezes in Safari, try Chrome or Firefox to see if the issue persists.

4. Check for Mac System Updates: Sometimes system updates fix bugs. Go to Apple menu > System Preferences > Software Update.

5. Disable Browser Extensions: Extensions sometimes interfere with sites. Try disabling them temporarily.

If the problem is from a UHC app installed on your Mac (less common), consider uninstalling and reinstalling it, as corrupted app data can freeze screens.

Please let me know more details about how and when the freezing occurs, and what you've tried so far. That way, I can suggest more targeted solutions!