Oh, I have already been using the AutoCorrect settings to instantly make the change as you type along. The Preflight is new to me, but not much of a help when you have a hundred pages of text I grab from the web. Can be extremely tedious. However, it does help to use on short documents. Thanks for your help and suggestions, and I will definitely be using this technique. For large documents, I will stick to the MS Word way and re-import back to Affinity Publisher when done. We need to be resourceful and adapt to the limitations of our tools.
If the Affinity suite of applications does not have a better Find and Replace functionality in the next version update of Affinity, I will skip the upgrade and wait until they do.