How to encrypt each PDF file with individual password?

How to use serial letter field for naming PDF files in mail merge...
 

Click Mail Merge into Multiple Files. A dialog will be open.

If you type in the field Password a text value, e.g. abc - Edi will encrypt all PDF files with the same password.

However - if you define a data column with a custom value for each customer, each PDF document will be encrypted individually.

Just select this column from the list and double click it or click the Insert button for inserting a field into the text box Password.