A better way to change straight quotes to curly is probably to use AutoFormat.

1. This probably too late for you unless you have the original text.
2. Microsoft has hidden this function away in the Ribbon version but it should be under Tools..
3. You need to add it to the Quick Access Toolbar.

The settings are like those for AutoFormat as you type.


You can reach them under Tools > AutoCorrect Options. In Ribbon Versions, this is under File > Options > Proofing > AutoCorrect Options.