You didn’t mention, if you have upgraded to 24.8, or you installed LibreOffice for the first time; and if you upgraded, then from which version.
Why could that be important? Because (1) in version 7.2, we have removed the “toggle Track Changes” keyboard combination (tdf#130847), because the previous Ctrl+Shift+C was close to Ctrl+C, causing accidental misclicks toggling the function inadvertently; and (2) in the same version 7.2, we have introduced the infobar to inform users about the active Track Changes function (tdf#125909), because having it enabled without a notice is actually a privacy problem, when you may not realize that the document you are editing and then sending someone may contain, beyond the content you see on screen, the history of all the edits, so the text you deleted long ago.
And if you, say, used LibreOffice 6.2, accidentally enabled the function on a file, disabled the display of the function (not a wise decision anyway!), and thought you were done - then used that document to create hundreds of copies to start new documents … then upgraded to 24.8, then you simply became aware of the trap you had all this time (that got worse with each copy of that track-changes-enabled document). It’s not 24.8; it’s not something as easy as “turn it off once and forever”, it’s a work you have to do in all affected files.
But it of course could be something else - if my assumption about upgrade from pre-7.2 version is wrong.