Are they in Person Notes? For the focus person go to the Person tab and these are on the bottom of the screen. There should be a panel at the bottom with Notes, Media, Web Links & Tasks. If you can't see that it's been minimized and double clicking on the 8 little dots will reset this panel.
Research notes are also in that panel. Click on the paper & pencil (2nd icon on the left).
Research notes are also in that panel. Click on the paper & pencil (2nd icon on the left).