I am working on my doctoral project. I need to take a KJV Bible and edit it with some language specific corrections. I need to be able to for example take an older English word such as "thou" and change every instance of the word to "thou(ss)" where the (ss) is not in brackets, but rather the "ss" is a superscript. I need to be able to change all instances at the same time.

Typical Word Processing programs cannot do that, with the exception of WordPerfect by Corel, which I do not own and has other limitations.