I'm putting Photoshop CS5 on my new windows laptop. The new laptop is a 4k touchscreen laptop. When I installed it everything went correctly except all the dialog boxes (file, edit, etc) and the add-ons, (layers, etc) are all tiny I'm attaching a picture of my screen to give you an idea of what it looks like. The preference -> interface -> is set to large. Any help to resolving this would be great appreciated. Thanks!
CS 5 does not have a scalable UI, so when you increase the pixels to inch ratio of your monitor ( a 4K monitor has tiny pixels) the UI appears smaller on screen.
Continuing on that thought, you can lower the resolution of your display, and the interface will appear larger (negating the advantage of a HiDPI display) or upgrade to CC which offers scaling to address this specific issue.