Isn't it usually the prepositions "about" and "on" that are ambiguous at times? I'm not certain that either "in" or "about" works in the context of sentence you provided. Perhaps you meant this? "I have spent much time attempting to understand the use of this English word on the web site." When I use prepositions in English, instead of remembering rules, I search for examples of usage. This web page provides some examples as well as guidelines: https://www.englishforums.com/English/WhenPrepositionsAboutOn/lvqxw/post.htm