At the left side in Menu Bar, there is option of button "Setting". You can find setting option in "My account" as well. We have to click on it.
After clicking on the setting, we will go in the option "Quotation", here we will click on the "PDF Header".
Here we can write which we want to header on the top of the Quotation page. Like : Quotation, Quotation copy etc.
After that we will click on the button "Update".