Hi there orietta244,
It sounds like you're unable to trust your computer from your iPhone. We'd like to share a resource that might help.
Check it out here: About the 'Trust This Computer' alert on your iPhone, iPad, or iPod touch
Specifically, you'll want to review any steps you haven't yet taken under the "Get help" section:
"If you tap Trust or Don't Trust but doesn't accept your answer, or if the Trust alert won't appear, follow these steps. Try again after each:
- Make sure that your computer has the latest version of macOS or the latest version of iTunes.
- Disconnect and reconnect your device from your computer.
- Restart your computer.
- Restart your device:
5. Reset your Trust settings.
If the above steps don't help, go to Settings > General > Reset and tap Reset Network Settings. This also resets Wi-Fi networks and passwords, cellular settings, and VPN and APN settings that you’ve used before."
We hope this helps!