Brother MFC-3420C - Manual (Page 27)

USING THE MACHINE AS A PRINTER 1 - 19
Device Options
Lets you set the following Printer Functions:
Print Date & Time
When enabled the Print Date and Time feature will print the date
and time on your original from your computer’s system clock.
Click the Setting button to change the Date and Time format, and
the Position and the Font. To include a background with the Date
and Time, select Opaque. When Opaque is selected, you can click
on the Color button to change the color of the Date and Time
background.
The Date and Time in the selection box shows the format that will
be printed. The actual Date and Time printed on your original is
automatically retrieved from the settings of your computer.