My selection tool icon in adobe illustrator has changed to a triangle, Does anyone know what that means and how I can turn it back to the arrow icon?
These are the new icons for the selection tools in Illustrator CC (2017).
From the "Illustrator New features" section on the Adobe Illustrator page:
Modern user experience
A flat UI and new icons for tools and panels offer a cleaner look and help you focus on your artwork.
I don't think there is a built in way to change them back.