Smart quotes in imported text

I have imported a large quantity of text which has “non-smart” quotes. If I manually edit, deleting each quote mark and typing it again, they are automatically converted to smart quotes as I type. However, is there a way in which I can easily convert all the quote marks in the selected text/document/project to smart quotes? Find and replace does not seem to do this. Neither does cutting and pasting blocks of text containing the non-smart quotes.

Thank you. I am embarrassed to have missed something so obvious.