It can be modified directly in the mobile phone client of the corresponding bank. The following is an example of the modification of Agricultural Bank of China. The method is as follows:

1. Open the mobile client of Agricultural Bank of China, as shown in the figure below.

2. Next, enter the client and log in to your bank account.

3. Then select my account, as shown by the arrow in the figure below.

4. Enter the "My Account" page, and select the setting option shown by the arrow in the figure at the top right.

5. Next, select "Debit Card Encryption" indicated by the arrow in the list.

6. Then enter the password you want to modify in the page according to the prompt, and click "OK".