如果不用保存历史，换个手机号就行。。。

When in signal app, click 3 little dots on top-right, then settings, advanced,

Turn off "signal messages and calls" (that is unregister the phone number)

Turn back on and enter your new number (that is registering your new number).

Of course you need to let your friend know your new phone number

If you want the app to retain the chart history, you need to give the app.a pin