You're right, you can't do this directly with Find and Replace, because if you specify formatting for the "Replace with" text, it applies to the whole of that text. But what you can do is replace with the contents of the Clipboard. To do so, enter the text you want in your document, select it, and press Ctrl+C to copy it. Press Ctrl+H to display the Find and Replace dialog box, type the search text into the "Find what" box, and type
^c in the "Replace with" box. Word then replaces the found items with the contents of the Clipboard.
Another trick that's sometimes useful is to use two replace operations: one to isolate the text you want to affect, and the second to apply the change. This technique also works for replacing "SO2" with "SO2". In the first replace operation, replace "SO2" with "SO" concatenated to a text string that will distinguish the "2" from instances of "2" that don't need to be changedfor example, "SOzx2zx." In the second replace operation, replace "zx2zx" with a subscript "2."
Perform a Two-Step Replace
Okay, picture this: I've got a 500-page document with several thousand references to our product, the Bovine Super Defibrillator. Only sometimes it's just called the Super Defibrillator. I need to change all the instances to "Bovine Super Defibrillator." But if I do a Replace All, all the instances that already have "Bovine" change to "Bovine Bovine Super Defibrillator," which I don't want. And if I don't do a Replace All, I need to accept or reject the replacements one at a time.
It's okay. Do the Replace All. Then do a Replace All of "Bovine Bovine" with "Bovine." Problem solved.