Instead of selecting words or whole paragraph appears the dictionary with the word I´m highlighting. I´m not able to delete a whole sentence. I have to do it word by word, and not all together.
This is probably a Mac OS issue rather than something Scrivener-specific. Do you see the same behavior in TextEdit?
As a first step, I would check to see what mouse/trackpad gestures are configured in System Preferences.
If the dictionary appears, you might be clicking too hard on the trackpad. I tend to disable “force click” in the Trackpad pane of System Preferences, as I’m always accidentally pressing too hard and it goes past a regular click, into look-up mode.