how can i trust my pc? really irritate with this problem.

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Hi,

Thank you for your question.

How to manage your Windows Account:
If you have mades changes to your personal master data, i.e. a phone number, you can change that as well.
Go here http://account.live.com and login to your account - i.e. the same user name and password you used in Windows 8 for connecting to the Windows cloud - and obtaining the "Trust this PC" prompt under the connected user. Update i.e. the phone number.
Trust
Guess you're reffering to the message prompt "Trust this PC", i.e. at WinKey + C > Settings > Change PC Settings > Users > Trust this PC.
You simply click the link ... goto WinKey + C > Settings > Change PC Settings > Users > Trust this PC and click Trust this PC.
When you create a new trust relationship between your computer and the Windows cloud - i.e. you also do that when you break the relationship and then recreate it again (so do not join and disjoin your computer to the cloud too much - unless you don't mind to transact the entire joining process again including to certify the new trust relationship (another unique encrypted ticket). Trust this PC Means that you will allow that computer to read data from your personal account. I.e. you could use your friends computer and decide to trust that computer - if you did you would allow his computer to sync your data onto its disks depending on your setup. So that's the great thing - you can use other computers - but not sync automatically unless you trust that computer (i.e. you own it).
BTW  Changing phone numbers and joining a central computer system like the cloud works the same at Googles , Apples ... if not, those services are not as safe (syncing to any computer? Not Windows) or flexible (you can actually login to different computers including at work using your account - and use the apps seamlessly).

We could refer to the following link:

https://social.technet.microsoft.com/Forums/windows/en-US/af149efd-83c8-4408-8234-26ad0ec910c4/trust-this-pc-how?forum=w8itprosecurity

If there are any questions regarding this issue, please be free to let me know.

Best Regard,

Jim