To change your trust number, please go to the "secure account" section by clicking on the profile at the top right of the screen. Then click on the name / first name.
If your smartphone is already registered, the change of trust number will be done automatically, even in Wi-Fi if you have no phone network.
If your smartphone is not registered, you will receive an SMS code on your old trusted number.
*Please note that changing the number in the contact section will have no effect.