Hi andyf,
Thanks for contacting Apple Support Communities!
We understand that you're continually seeing an alert to trust your computer although you already have.
You may need to update iTunes, reset your Trust Settings and ensure that Mobile Device Helper is enabled in your startup items as outlined here: About the 'Trust This Computer' alert on your iPhone, iPad, or iPod touch
"Get help
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:
iPhone
iPad
iPod touch
5. Reset your Trust settings.
If the above steps don't help, go to Settings > General > Transfer or Reset [Device] > 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.
If you downloaded iTunes for Windows from the Microsoft Store, make sure that iTunes Mobile Device Helper is enabled as a startup item.
If you still need help, contact Apple Support."
We hope this helps.
Cheers!
