How do I turn off the Highlight tool?

I have tried the following three things:

(1) Tools > Comment and Markup > [tried clicking on "Highlight Text tool" to un-check it, but the check mark remains].

(2) Comments > Comment and Markup Tools > Highlight Text tool (clicked on it to uncheck, but again, check mark remains)

(3) View > Comment and Markup > [clicked on the Highlight tool icon--which I had done to open it--but it remains shaded, meaning that it is still on]

Any help appreciated. Thank you.