First, open the settings of the mobile phone interface, then click the desktop and wallpaper, and you can see the lock screen signature at the bottom of the page, and open the lock screen signature;

An edit box will pop up, click OK after editing the signature, and return to the desktop and wallpaper interface to see that the lock screen signature has been updated to the signature you just edited;

Lock the phone screen, then open it again, and you can see your lock screen signature in the lower right corner of the lock screen page.