Is this a written manual that you're looking to log changes in? Or digital document? Personally I favor a well documented "history of changes" section at the end of each document that records what aspects were changed, when, and by whom. I have never used strikethroughs or highlighting within the document to show these changes, and it has never been an issue with auditors. Too many strikethroughs/underlines/highlights in a document make it annoying on the eyes to read in my opinion.
If anything I would only opt to highlight the most recent change in the document, provided it's an important procedural change that you want readers to take notice of. I wouldn't highlight or strikethrough corrected typos, because that seems confusing. So to answer your question, the only "standard" with changelogs I've heard of in our industry (I have FDA and SQF experience) is that you need to have a way to keep track of your revision history (what was changed, and how can you ensure the most up-to-date version is available to staff).