How do you set preferred units of measure?

I grew up with what we quaintly called Imperial* Units of Measure – inches, acres, pints, pounds, etc. But Australia has been a metric country for decades, so that anyone under 40 yoa will have no idea what these mean. Where can I set preferences/options for metric units of measure for page sizes, etc.? Or for typographic measurements, use of points, ens, ems, picas, etc? Or mixtures – mm for page sizes, margins, and footer/header frame sizes and offsets from page edge, but printer’s units for typeface size, line spacing, indentation, etc.?

Tools->Options->Editor->Ruler Units.