Hello rdr,
Thank you for your post.
To move the cursor to the next/previous frame you can use "Ctrl + Right"/"Ctrl + Left" hot keys.
"Right" and "Left" buttons are for navigation to the next/previous K frame.
Up/Down hot keys are for navigation 1/20th forward/backward.
You can find the whole list of navigation commands and their hot keys in the "Navigation" menu or in Tools -> Preferences.