I would like to know, how I can adjust DPI preview of documents in InDesign and Photoshop. In Acrobat I can easily change resolution to custom (in my case I want 109 pixels/inch - 2560x1440 on 27') and 100% preview is correct (when I put A4 paper on screen it fits). How can I adjust it in other Adobe software? PS in ID has both lower resolution by default (96 i guess?).
InDesign CS6 or later displays the actual print size when you view at 100%—it automatically detects your main monitor's resolution to display the actual print size. At 100% your ruler dimensions will view at their actual size.
The current Photoshop will give you the actual print size if you choose View>Print Size. In that case the zoom percentage will depend on both your monitor's and the document's resolution. Photoshop's 100% view has always previewed the image at a 1:1 monitor pixel to image pixel ratio, and would not show the actual print size unless the image resolution happened to match your monitor resolution.
Prior to CS6 InDesign also used the 1:1 ratio for 100% views and in that case you were not seeing the actual print size.