Go to the relevant area of the system to generate a layout, e.g. from a Task, Quote, Invoice, Purchase Order, Work Order, etc.
Scroll down to the Print Options (bottom of screen).
Select the standard layout that you would like to customise.
The image above shows the layouts available on an Invoice screen, however, you will find that there are different standard layouts available depending on the type of layout or area of the system that you're generating it from.