Why did you go to the bank to change your signature to blank paper?
The reason why I went to the bank to change my signature is blank paper, in order to facilitate and save trouble. In order to save time, the teller will sign the blank paper first. At this time, the teller is printing the blue color at the back, and put it into the machine for printing after signing. This won't have any effect on the money changers, so don't worry.