cursor doesn't work correctly in Windows or Pages

When typing a sentence and hitting return or cut and pasting. The cursor remains where it last was and flashes a purple color. I've tried all I know. I know there's an update for Windows which I won't buy. So I went back to Pages. And the same mishap is happening.

ex. If I want the cursor to be in the middle of the sentence to add more words, I move the cursor to said position. But when I start typing, the cursor remains in the old position and starts typing. The same behavior happens in both programs.