Why Are All The: Icons On My Desktop Big

Go to Settings > System > Display and check the "Scale" percentage. It should usually be at 100% or 125% .

If you didn't use the scroll wheel, you may have accidentally triggered a View setting via the context menu. why are all the icons on my desktop big

Because the scaling happens in real-time, a single heavy scroll can blast your icons from "Medium" to "Extra Large" in a split second. Go to Settings > System > Display and