When I watch videos, the tape measure tool is always yellow when attempting to scale an image correctly. They toggle between tape measure tool options with the “option” button, but mine never turns yellow.
Those are old videos you’re watching. The cursors were changed a while back. Don’t fixate on the color of the cursor. The thing that changes is the display of the red guidepoint at the top left. Tapping Option on Mac turns that on an off.