Rolling over text to mark for commenting produces erratic results, e.g., first word highlighted and then no others even though mouse has not been released. How do I fix this?

I have Acrobat Pro DC and Windows 10.  When attempting to make editing comments, I find it almost impossible to get the words marked (by rolling over them with the mouse button pressed).  The blue highlighting jumps around from word to word or quits after rolling over a single word even though the mouse button has not been released.

Furthermore, now that the strike-and-replace tool has been eliminated, you are supposed to perform the same operation by rolling over the text to be replaced and, once the desired text has been blue-highlighted, simply begin typing the new text.  This works unreliably.  After finally getting the proper text marked, I start typing and nothing happens.  I may have to select a tool (such as strike-out), use it, and delete the strike-out, before the strikeout-and-replace operation will again work.

I have used older versions of Acrobat Pro (on Vista) without any such problems.