You most possibly have unaccepted tracked changes in your document. Possibly even still recording, just not shown. If you don’t need to track changes, then you don’t need to turn their display off (as is your case); instead, you must turn off the tracking itself, and also accept (or reject, but that’s improbable in your case) already made changes. This way you make sure that there are no tracked changes left in the document, and then you turn their display on, to immediately see if a document has these.
Disabling the changes display is only useful when one works with the changes (possibly with colleagues who use them), and wants to keep them, but (temporarily) wants to not see them to work with document comfortably.