PPM administrators can hide native workspace fields by workspace type.
Any fields hidden for your workspace type will not appear in the Update Status window. This may change the look of the window significantly. For example, if all the default calculated fields on the left side of the window (like Total Scheduled Work) are hidden, that section of the window is hidden entirely.
In this image, two derived fields have been hidden (Scheduled and Actual Work on the left, and the status field Estimated Expenses on the right.
(click outside window to close)