Header and footer text can be set in Sheet Properties.  Control characters (i.e. /p) allow you to customize the position and appearance of the header text. The toolbar in the Header/Footer setting allow you to insert the most commonly used control characters. 

Use the control characters before the text that you want to customize. If you use multiple control characters, do not put spaces between them. The following control characters are available:

Control Character	Description
/n	New line
/l	Left aligns text
/r	Right aligns text
/c	Centers text
/date	Adds current date
/dl	Adds current date in long date format
/ds	Adds current date in short date format
/time	Adds current time
/tl	Adds current time in long date format
/ts	Adds current time in short date format
/p	Inserts page number
/pc	Inserts page count
//	Prints a slash character (/)
/fn	Font name, must be enclosed in quotes.  Not supported at this time.  Future.
/fz	Font size in points, must be enclosed in quotes
/fb0	Font bold off
/fb1	Font bold on
/fi0	Font italics off
/fi1	Font italics on
/fu0	Font underline off
/fu1	Font underline on
/fk0	Font strikethrough off
/fk1	Font strikethrough on
/sn	Facility name
/sa	Facility site address
/scsz	Facility city state zip
/un	Username