I've just watched a tutorial using a Mac to create a preset to export, where the photographer was able to specify the size of the file as 1600 x 1000, with a 72 ppi - to be used for sharing to the web, and then another preset that changed those details specifically for printing. I don't seem to be able to do that. I can't work out if its the version of Lightroom I'm using, or if it's a Mac v Windows thing. Can someone please show me how to do this? Thanks!
How to, Import and share, Presets or profiles, Windows
You may have been watching a tutorial for Lightroom Classic. If you are using Lightroom 3.3, I don't believe you will find that you have the same options available to you. The export function is much more limited in its capabilities in that version.