To alter the title (and sub-title) or your sales quote, this can be done within the Sales Quote Editor a couple of ways by following the steps below:
The simplest way to edit the document title is by clicking the top bar in the Sales Quote Editor.
This will take you directly to the Cover Page Settings. In the right-hand settings, click on the Title field to change the document title. Continue this same process for the Subtitle field if required.
If you want to confirm that your changes have been made, you can view this in the editor by toggling from "Edit" mode to "Preview" mode at the top of the screen, as shown below.
You are also able to bring up the Cover Page Settings from anywhere within the Sales Quote Editor by clicking on ... More in the right-hand panel, and select Cover Settings.
This will bring up the same settings panel as shown above.
It is important to note that you are able to edit the document title and sub-title manually in the text field on the cover page, however making the change this is not advised, as this removes the field merge formula and while it changes the text, it doesn't change the actual Sales Quote information.