Issues with Rotate Tool and Rotating an object by 90 Degrees

Hi there I have followed the your instructoons to the T, I’ve notice when you click on the nose and adjust the rotation tool, the action after is slightly more tha 90 degrees. This is where I am having problems, as when then I try to rotate the whole object, the object is only be rotated from the nose. I keep trying, but would welcome any suggestions where I am going wrong.

Wez