Changing an existing palette item

I have a palette item - system text in the Line category:

"poco rit----------"

I want to change it - in the Palette box - to simply say "rit.--------", and have the result be "rit.-----" without having to open Properties and delete the word "poco" every time I need that item. I've enabled editing but don't see a way to make this change. Is there a way to do this, or do I have to start over and create it from scratch?

Thanks.