Use Edit>Replace, click on the More button and then with the cursor in the
Find what control, click on Format in the Replace dialog and then on Font
and in the Format Fond dialog, use the Colour control to select the grey
that you are talking about (there are many of them and you will need to get
the right one) then move the cursor to the Replace with control and once
again click on Format and then Font and this time select Automatic from the
Colour control.  Then click on Replace All.