The right angled triangle pirouetted and transformed, much to the delight of the ice cream

Tear me off, scratch my head. What's now black was once red.

Use your singular of this to solve this riddle I made it easy, making it liddle Goes well with butter Or pesto, marinara, or Bolognese if you prefer.

A heavy weight upon your back, Whether responsibility or horse's tack, You're sat in this if you have control, Grab the reins or handlebars and go!

Most people don’t think about me until a little icon turns red.