How to customize title when using print()?

The print() method uses the title of the current page when printing.

You can temporarily override the title like this:

const oldTitle = document.title;
document.title = "My Scheduler";
dp.exportAs(format).print();
document.title = oldTitle;

If you need full control over the layout of the output page, I recommend exporting the Scheduler to PDF:
https://doc.daypilot.org/scheduler/client-side-pdf-export/