You might like to take a look at ChangedRecordDemo.zip in my public databases folder at:
If you have trouble downloading a specific file, clicking on the 'Download' button at the top of the page while no files are selected should download a zip file of all files in the folder, from which you should then be able to unpack the relevant file.
This little demo file illustrates a number of ways to time stamp or log changes to data. Including an option to insert rows into an audit tail table.
The key thing about this demo is that it detects actual changes to data rather than merely updates. A row in a table can be updated without the values of the data actually changing.