You'll have to either (copy and) move the expression to a different category, create the expression in the Misc. category, or change the Score List settings in the Category Designer.

The idea is that certain expressions, like tempo marks and tempo changes, apply to all staves and therefore don't need to be on every staff in a score or, in large scores, perhaps only on the top staff of each group. These are shown only on each part. As George mentioned, this is done with Score List settings. Other expressions, like dynamics, do need to be shown on every staff, as they are often not global. Besides its not being officially correct to show tempo marks and tempo changes on every staff in a score, it produces a lot of unnecessary clutter.