Size Marks is a helpful Photoshop script for web designers and front-end engineers which converts rectangular marquee to labeled measurement mark.

You can quickly change the unit of measure in a document by right-clicking anywhere in the document rulers and selecting your preferred unit of measure.

If you’re annoyed when you open a new InDesign document and the unit of measure is not what you prefer, you can set the preferences to always create new documents using inches (or any other unit you prefer). Simply close all InDesign documents and set your preferred unit of measure in Preferences>Units & Increments. From that point forward, all new documents will use that unit of measure by default.