After modifying setting values, click the UPDATE button to put the new
values into effect.

When entering a new value for the Print Width setting, be certain to follow
the numerical value with a valid unit of measurement, such as in for inches,
cm for centimeters, etc... A blank space between the numeric value and the
unit of measurement will generate an error.

Examples - Legal: 7.5in    Illegal: 7.5 in

7.5in is the default setting for US letter size paper set to print in portrait
mode and 190mm is correct for A4.