I am only looking at a user story or defect and yet the revision history is showing that I made updates when I did not.
This issue is caused by a Browser Extension/Plugin called Selenium. This is not provided by or installed/supported by CA and is known to cause Agile Central to record revision updates.
In order to prevent updates to the revision history, please disable the extension. You may also wish to investigate an option to white-list the Agile Central domain or IP addresses - if you use the Selenium plugin in your daily activities.