Is there any way to change the default printing settings in the dialog box?
For instance, I would like the paper format to be always
A4. Now it always appears as
US letter by default and I have to change it each time.
You can use Cups administration page. You can access it by opening
Then select Administration -> Manage Printers
Select your printer and then, on the "Administration" dropbox choose "Set Default options". Change the default settings and finally press "Set default options". If it asks you the username/password use the same combination you use to login.